Polynomial Problems and Solutions
1-Mark Questions
1
If x ≠ –1, then find the quotient of (x⁵ + x⁴ + x³ + x²) / (x³ + x² + x + 1)
(M'15)
Step 1: Factor numerator and denominator
Numerator: x⁵ + x⁴ + x³ + x² = x²(x³ + x² + x + 1)
Denominator: x³ + x² + x + 1
Numerator: x⁵ + x⁴ + x³ + x² = x²(x³ + x² + x + 1)
Denominator: x³ + x² + x + 1
Step 2: Simplify the expression
(x⁵ + x⁴ + x³ + x²) / (x³ + x² + x + 1) = [x²(x³ + x² + x + 1)] / (x³ + x² + x + 1)
(x⁵ + x⁴ + x³ + x²) / (x³ + x² + x + 1) = [x²(x³ + x² + x + 1)] / (x³ + x² + x + 1)
Step 3: Cancel common factors
Since x ≠ -1, (x³ + x² + x + 1) ≠ 0, so we can cancel:
= x²
Since x ≠ -1, (x³ + x² + x + 1) ≠ 0, so we can cancel:
= x²
∴ Quotient = x²
2
"We can write a trinomial having degree 7". Justify the above statement by giving one example.
(M'15)
Step 1: Understand the terms
- A trinomial is a polynomial with exactly three terms.
- Degree of a polynomial is the highest power of the variable.
- A trinomial is a polynomial with exactly three terms.
- Degree of a polynomial is the highest power of the variable.
Step 2: Create an example
Example: 3x⁷ + 2x³ + 5
This has:
- Three terms: 3x⁷, 2x³, and 5
- Highest power: 7
- Therefore, it's a trinomial of degree 7.
Example: 3x⁷ + 2x³ + 5
This has:
- Three terms: 3x⁷, 2x³, and 5
- Highest power: 7
- Therefore, it's a trinomial of degree 7.
∴ Example: 3x⁷ + 2x³ + 5
This is a trinomial with degree 7, which justifies the statement.
This is a trinomial with degree 7, which justifies the statement.
3
Write an example for a quadratic Polynomial that has no zeros.
(M'16)
Step 1: Condition for no zeros
A quadratic polynomial has no real zeros when its discriminant (D = b² - 4ac) is negative.
A quadratic polynomial has no real zeros when its discriminant (D = b² - 4ac) is negative.
Step 2: Create an example
Let's take p(x) = x² + 2x + 3
Discriminant D = b² - 4ac = (2)² - 4(1)(3) = 4 - 12 = -8 < 0
Since D < 0, this quadratic has no real zeros.
Let's take p(x) = x² + 2x + 3
Discriminant D = b² - 4ac = (2)² - 4(1)(3) = 4 - 12 = -8 < 0
Since D < 0, this quadratic has no real zeros.
∴ Example: x² + 2x + 3
This quadratic polynomial has no real zeros as its discriminant is negative.
This quadratic polynomial has no real zeros as its discriminant is negative.
4
If p(x) = x³ – 3x² + 2x – 3 is a polynomial, then find the value of p(1).
(J'16)
Step 1: Substitute x = 1
p(1) = (1)³ - 3(1)² + 2(1) - 3
p(1) = (1)³ - 3(1)² + 2(1) - 3
Step 2: Calculate
p(1) = 1 - 3 + 2 - 3
p(1) = 1 - 3 + 2 - 3
Step 3: Simplify
p(1) = (1 + 2) + (-3 - 3) = 3 - 6 = -3
p(1) = (1 + 2) + (-3 - 3) = 3 - 6 = -3
∴ p(1) = -3
5
Srikar says that the order of the polynomial (x² – 5)(x³ + 1) is 6. Do you agree with him?
(J'17)
Step 1: Expand the polynomial
(x² - 5)(x³ + 1) = x²(x³ + 1) - 5(x³ + 1) = x⁵ + x² - 5x³ - 5
(x² - 5)(x³ + 1) = x²(x³ + 1) - 5(x³ + 1) = x⁵ + x² - 5x³ - 5
Step 2: Rearrange in standard form
= x⁵ - 5x³ + x² - 5
= x⁵ - 5x³ + x² - 5
Step 3: Find the degree
The highest power of x is 5, so the degree (order) is 5.
The highest power of x is 5, so the degree (order) is 5.
∴ I don't agree with Srikar.
The order of the polynomial is 5, not 6.
The order of the polynomial is 5, not 6.
6
Find zeros of the polynomial P(x) = x² – 4.
(J'17)
Step 1: Set P(x) = 0
x² - 4 = 0
x² - 4 = 0
Step 2: Solve for x
x² = 4
x = ±√4 = ±2
x² = 4
x = ±√4 = ±2
∴ Zeros are x = 2 and x = -2
7
Verify the relation between zeros and coefficients of the quadratic polynomial x² – 4.
(M'18)
Step 1: Identify coefficients
For x² - 4:
a = 1, b = 0, c = -4
For x² - 4:
a = 1, b = 0, c = -4
Step 2: Find zeros
Zeros: α = 2, β = -2
Zeros: α = 2, β = -2
Step 3: Verify sum of zeros
α + β = 2 + (-2) = 0
-b/a = -0/1 = 0
∴ α + β = -b/a
α + β = 2 + (-2) = 0
-b/a = -0/1 = 0
∴ α + β = -b/a
Step 4: Verify product of zeros
αβ = (2)(-2) = -4
c/a = -4/1 = -4
∴ αβ = c/a
αβ = (2)(-2) = -4
c/a = -4/1 = -4
∴ αβ = c/a
∴ The relation between zeros and coefficients is verified:
Sum of zeros = -b/a = 0
Product of zeros = c/a = -4
Sum of zeros = -b/a = 0
Product of zeros = c/a = -4
8
Whether 1/2 and 1 are zeros of the polynomial p(x) = 2x² – 3x + 1 or not? Justify.
(J'18)
Step 1: Check if 1/2 is a zero
p(1/2) = 2(1/2)² - 3(1/2) + 1 = 2(1/4) - 3/2 + 1 = 1/2 - 3/2 + 1 = -1 + 1 = 0
∴ 1/2 is a zero.
p(1/2) = 2(1/2)² - 3(1/2) + 1 = 2(1/4) - 3/2 + 1 = 1/2 - 3/2 + 1 = -1 + 1 = 0
∴ 1/2 is a zero.
Step 2: Check if 1 is a zero
p(1) = 2(1)² - 3(1) + 1 = 2 - 3 + 1 = 0
∴ 1 is a zero.
p(1) = 2(1)² - 3(1) + 1 = 2 - 3 + 1 = 0
∴ 1 is a zero.
∴ Both 1/2 and 1 are zeros of the polynomial p(x) = 2x² - 3x + 1.
9
If P(x) = x⁴ + 1, then find P(2) – P(-2).
(M'19)
Step 1: Calculate P(2)
P(2) = (2)⁴ + 1 = 16 + 1 = 17
P(2) = (2)⁴ + 1 = 16 + 1 = 17
Step 2: Calculate P(-2)
P(-2) = (-2)⁴ + 1 = 16 + 1 = 17
P(-2) = (-2)⁴ + 1 = 16 + 1 = 17
Step 3: Find P(2) - P(-2)
P(2) - P(-2) = 17 - 17 = 0
P(2) - P(-2) = 17 - 17 = 0
∴ P(2) - P(-2) = 0
10
–3, 0 and 2 are the zeroes of the polynomial p(x) = x³ + (a – 1)x² + bx + c. Find a and c.
(J'19)
Step 1: Use the zero x = 0
p(0) = (0)³ + (a - 1)(0)² + b(0) + c = c
Since 0 is a zero, p(0) = 0, so c = 0
p(0) = (0)³ + (a - 1)(0)² + b(0) + c = c
Since 0 is a zero, p(0) = 0, so c = 0
Step 2: Use the zero x = 2
p(2) = (2)³ + (a - 1)(2)² + b(2) + 0 = 8 + 4(a - 1) + 2b = 0
8 + 4a - 4 + 2b = 0
4a + 2b + 4 = 0
2a + b + 2 = 0 ...(1)
p(2) = (2)³ + (a - 1)(2)² + b(2) + 0 = 8 + 4(a - 1) + 2b = 0
8 + 4a - 4 + 2b = 0
4a + 2b + 4 = 0
2a + b + 2 = 0 ...(1)
Step 3: Use the zero x = -3
p(-3) = (-3)³ + (a - 1)(-3)² + b(-3) + 0 = -27 + 9(a - 1) - 3b = 0
-27 + 9a - 9 - 3b = 0
9a - 3b - 36 = 0
3a - b - 12 = 0 ...(2)
p(-3) = (-3)³ + (a - 1)(-3)² + b(-3) + 0 = -27 + 9(a - 1) - 3b = 0
-27 + 9a - 9 - 3b = 0
9a - 3b - 36 = 0
3a - b - 12 = 0 ...(2)
Step 4: Solve equations (1) and (2)
From (1): b = -2a - 2
Substitute in (2): 3a - (-2a - 2) - 12 = 0
3a + 2a + 2 - 12 = 0
5a - 10 = 0
a = 2
From (1): b = -2a - 2
Substitute in (2): 3a - (-2a - 2) - 12 = 0
3a + 2a + 2 - 12 = 0
5a - 10 = 0
a = 2
∴ a = 2, c = 0
11
Write any two linear polynomials having one term under three terms.
(J'19)
Step 1: Understand linear polynomials
A linear polynomial has degree 1 and can have 1, 2, or 3 terms.
A linear polynomial has degree 1 and can have 1, 2, or 3 terms.
Step 2: Examples with one term
1. 5x (degree 1, one term)
2. -3x (degree 1, one term)
1. 5x (degree 1, one term)
2. -3x (degree 1, one term)
Step 3: Examples with three terms
1. 2x + 3y + 4 (degree 1 in x and y, three terms)
2. x + y - 2 (degree 1 in x and y, three terms)
1. 2x + 3y + 4 (degree 1 in x and y, three terms)
2. x + y - 2 (degree 1 in x and y, three terms)
∴ One-term examples: 5x, -3x
Three-term examples: 2x + 3y + 4, x + y - 2
Three-term examples: 2x + 3y + 4, x + y - 2
12
If p(x) = x² + 3x + 4, then find the values of p(0) and p(1).
(May 2022)
Step 1: Calculate p(0)
p(0) = (0)² + 3(0) + 4 = 0 + 0 + 4 = 4
p(0) = (0)² + 3(0) + 4 = 0 + 0 + 4 = 4
Step 2: Calculate p(1)
p(1) = (1)² + 3(1) + 4 = 1 + 3 + 4 = 8
p(1) = (1)² + 3(1) + 4 = 1 + 3 + 4 = 8
∴ p(0) = 4, p(1) = 8
13
If p(x) = 2x² + 5x – 7, then find the value of p(0) and p(1).
(Aug 2022)
Step 1: Calculate p(0)
p(0) = 2(0)² + 5(0) - 7 = 0 + 0 - 7 = -7
p(0) = 2(0)² + 5(0) - 7 = 0 + 0 - 7 = -7
Step 2: Calculate p(1)
p(1) = 2(1)² + 5(1) - 7 = 2 + 5 - 7 = 0
p(1) = 2(1)² + 5(1) - 7 = 2 + 5 - 7 = 0
∴ p(0) = -7, p(1) = 0
Polynomial-2 Marks
1
For what value of k, –4 is a zero of the polynomial x² – x – (2k + 2).
(J'15)
Step 1: Substitute x = -4 in the polynomial
p(x) = x² - x - (2k + 2)
p(-4) = (-4)² - (-4) - (2k + 2)
p(x) = x² - x - (2k + 2)
p(-4) = (-4)² - (-4) - (2k + 2)
Step 2: Simplify the expression
p(-4) = 16 + 4 - 2k - 2 = 18 - 2k
p(-4) = 16 + 4 - 2k - 2 = 18 - 2k
Step 3: Set p(-4) = 0 (since -4 is a zero)
18 - 2k = 0
18 - 2k = 0
Step 4: Solve for k
2k = 18
k = 9
2k = 18
k = 9
∴ k = 9
2
Use the table given below to draw the graph. Use the graph drawn to find the values of a and b.
(J'15)
Given table:
| x | -2 | 0 | 2 | 1 | b |
|---|---|---|---|---|---|
| y | -3 | 1 | a | 3 | -7 |
Step 1: Assume the relationship is linear (y = mx + c)
Using points (-2, -3) and (0, 1):
When x = 0, y = 1 ⇒ c = 1
Using (-2, -3): -3 = m(-2) + 1 ⇒ -3 = -2m + 1 ⇒ -2m = -4 ⇒ m = 2
∴ Equation: y = 2x + 1
Using points (-2, -3) and (0, 1):
When x = 0, y = 1 ⇒ c = 1
Using (-2, -3): -3 = m(-2) + 1 ⇒ -3 = -2m + 1 ⇒ -2m = -4 ⇒ m = 2
∴ Equation: y = 2x + 1
Step 2: Find value of a
When x = 2: y = 2(2) + 1 = 4 + 1 = 5
∴ a = 5
When x = 2: y = 2(2) + 1 = 4 + 1 = 5
∴ a = 5
Step 3: Find value of b
When y = -7: -7 = 2b + 1 ⇒ 2b = -8 ⇒ b = -4
When y = -7: -7 = 2b + 1 ⇒ 2b = -8 ⇒ b = -4
∴ a = 5, b = -4
3
Length of a rectangle is 5 units more than its breadth. Express its perimeter in polynomial form.
Step 1: Define variables
Let breadth = x units
Then length = (x + 5) units
Let breadth = x units
Then length = (x + 5) units
Step 2: Write perimeter formula
Perimeter = 2 × (length + breadth)
= 2 × [(x + 5) + x]
= 2 × (2x + 5)
Perimeter = 2 × (length + breadth)
= 2 × [(x + 5) + x]
= 2 × (2x + 5)
Step 3: Simplify to polynomial form
= 4x + 10
= 4x + 10
∴ Perimeter = 4x + 10
4
Show that 2 and −1/3 are zeros of the polynomial 3x² – 5x – 2.
(J'16)
Given polynomial: p(x) = 3x² - 5x - 2
Step 1: Check if x = 2 is a zero
p(2) = 3(2)² - 5(2) - 2 = 3(4) - 10 - 2 = 12 - 10 - 2 = 0
∴ 2 is a zero.
p(2) = 3(2)² - 5(2) - 2 = 3(4) - 10 - 2 = 12 - 10 - 2 = 0
∴ 2 is a zero.
Step 2: Check if x = -1/3 is a zero
p(-1/3) = 3(-1/3)² - 5(-1/3) - 2 = 3(1/9) + 5/3 - 2 = 1/3 + 5/3 - 2 = 6/3 - 2 = 2 - 2 = 0
∴ -1/3 is a zero.
p(-1/3) = 3(-1/3)² - 5(-1/3) - 2 = 3(1/9) + 5/3 - 2 = 1/3 + 5/3 - 2 = 6/3 - 2 = 2 - 2 = 0
∴ -1/3 is a zero.
∴ Both 2 and -1/3 are zeros of the polynomial 3x² - 5x - 2.
5
Which of √2 and 2 is a zero of the polynomial p(x) = x³ – 2x? Why?
(M'17)
Given polynomial: p(x) = x³ - 2x
Step 1: Check if x = √2 is a zero
p(√2) = (√2)³ - 2(√2) = 2√2 - 2√2 = 0
∴ √2 is a zero.
p(√2) = (√2)³ - 2(√2) = 2√2 - 2√2 = 0
∴ √2 is a zero.
Step 2: Check if x = 2 is a zero
p(2) = (2)³ - 2(2) = 8 - 4 = 4 ≠ 0
∴ 2 is not a zero.
p(2) = (2)³ - 2(2) = 8 - 4 = 4 ≠ 0
∴ 2 is not a zero.
∴ √2 is a zero of the polynomial, but 2 is not.
6
Divide x³ – 3x² + 5x – 3 by x² – 2. And verify the division lemma.
(J'17)
Division:
x - 3
-----------
x² - 2 | x³ - 3x² + 5x - 3
x³ + 0x² - 2x
-----------
-3x² + 7x - 3
-3x² + 0x + 6
-----------
7x - 9
Step 1: Result of division
Quotient = x - 3
Remainder = 7x - 9
Quotient = x - 3
Remainder = 7x - 9
Step 2: Verify division lemma
Division lemma: Dividend = Divisor × Quotient + Remainder
(x² - 2)(x - 3) + (7x - 9) = x³ - 3x² - 2x + 6 + 7x - 9 = x³ - 3x² + 5x - 3
This matches the original dividend.
Division lemma: Dividend = Divisor × Quotient + Remainder
(x² - 2)(x - 3) + (7x - 9) = x³ - 3x² - 2x + 6 + 7x - 9 = x³ - 3x² + 5x - 3
This matches the original dividend.
∴ Quotient = x - 3, Remainder = 7x - 9
The division lemma is verified.
The division lemma is verified.
7
Complete the following table for the polynomial y = p(x) = x³ – 2x + 3.
(M'18)
Given polynomial: y = x³ - 2x + 3
| x | -1 | 0 | 1 | 2 |
|---|---|---|---|---|
| x³ | (-1)³ = -1 | 0³ = 0 | 1³ = 1 | 2³ = 8 |
| -2x | -2(-1) = 2 | -2(0) = 0 | -2(1) = -2 | -2(2) = -4 |
| 3 | 3 | 3 | 3 | 3 |
| y | -1 + 2 + 3 = 4 | 0 + 0 + 3 = 3 | 1 - 2 + 3 = 2 | 8 - 4 + 3 = 7 |
| (x, y) | (-1, 4) | (0, 3) | (1, 2) | (2, 7) |
∴ The completed table is shown above.
8
If one of the zeros of the cubic polynomial p(x) = ax³ + bx² + cx + d is zero, then find the product of other two zeros of p(x). (a ≠ 0)
(J'18)
Step 1: Let the zeros be α, β, γ with γ = 0
So p(x) = a(x - α)(x - β)(x - 0) = a(x - α)(x - β)x
So p(x) = a(x - α)(x - β)(x - 0) = a(x - α)(x - β)x
Step 2: Expand the polynomial
p(x) = a[x³ - (α + β)x² + αβx] = ax³ - a(α + β)x² + aαβx
p(x) = a[x³ - (α + β)x² + αβx] = ax³ - a(α + β)x² + aαβx
Step 3: Compare with given form
p(x) = ax³ + bx² + cx + d
Comparing coefficients:
-a(α + β) = b ⇒ α + β = -b/a
aαβ = c ⇒ αβ = c/a
d = 0 (since constant term is 0 when one zero is 0)
p(x) = ax³ + bx² + cx + d
Comparing coefficients:
-a(α + β) = b ⇒ α + β = -b/a
aαβ = c ⇒ αβ = c/a
d = 0 (since constant term is 0 when one zero is 0)
Step 4: Product of other two zeros
The product of the other two zeros = αβ = c/a
The product of the other two zeros = αβ = c/a
∴ Product of other two zeros = c/a
9
Divide x³ – 4x² + 5x – 2 by x – 2.
(M'19)
Division using synthetic division:
x² - 2x + 1
-----------
x - 2 | x³ - 4x² + 5x - 2
x³ - 2x²
-----------
-2x² + 5x
-2x² + 4x
-----------
x - 2
x - 2
-----
0
Step 1: Result of division
Quotient = x² - 2x + 1
Remainder = 0
Quotient = x² - 2x + 1
Remainder = 0
Step 2: Verify
(x - 2)(x² - 2x + 1) = x³ - 2x² - 2x² + 4x + x - 2 = x³ - 4x² + 5x - 2
This matches the original dividend.
(x - 2)(x² - 2x + 1) = x³ - 2x² - 2x² + 4x + x - 2 = x³ - 4x² + 5x - 2
This matches the original dividend.
∴ Quotient = x² - 2x + 1, Remainder = 0
Polynomial Problems - 4 Mark Questions
1
Lakshmi does not want to disclose the length, breadth and height of a cuboid of her project.
She has constructed a polynomial x³ – 6x² + 11x – 6 by taking the values of length, breadth and height as its zeros.
Can you open the secret [i.e., find the measures of length, breadth and height]?
(M'15)
Step 1: Find the zeros of the polynomial
Given polynomial: p(x) = x³ - 6x² + 11x - 6
Given polynomial: p(x) = x³ - 6x² + 11x - 6
Step 2: Check for possible rational zeros
Possible zeros: ±1, ±2, ±3, ±6
Possible zeros: ±1, ±2, ±3, ±6
Step 3: Check x = 1
p(1) = 1 - 6 + 11 - 6 = 0
∴ x = 1 is a zero.
p(1) = 1 - 6 + 11 - 6 = 0
∴ x = 1 is a zero.
Step 4: Factor out (x - 1)
Using synthetic division:
Coefficients: 1, -6, 11, -6
Dividing by (x - 1):
Bring down 1, multiply by 1 → 1, add to -6 → -5, multiply by 1 → -5, add to 11 → 6, multiply by 1 → 6, add to -6 → 0
Quotient: x² - 5x + 6
Using synthetic division:
Coefficients: 1, -6, 11, -6
Dividing by (x - 1):
Bring down 1, multiply by 1 → 1, add to -6 → -5, multiply by 1 → -5, add to 11 → 6, multiply by 1 → 6, add to -6 → 0
Quotient: x² - 5x + 6
Step 5: Factor the quadratic
x² - 5x + 6 = (x - 2)(x - 3)
x² - 5x + 6 = (x - 2)(x - 3)
Step 6: Complete factorization
p(x) = (x - 1)(x - 2)(x - 3)
p(x) = (x - 1)(x - 2)(x - 3)
∴ The zeros are 1, 2, and 3
Therefore, the dimensions of the cuboid are:
Length = 3 units, Breadth = 2 units, Height = 1 unit (or any permutation of these values).
Therefore, the dimensions of the cuboid are:
Length = 3 units, Breadth = 2 units, Height = 1 unit (or any permutation of these values).
2
Draw the graph for the polynomial p(x) = x² + 3x - 4 and find its zeroes from the graph.
(M'15, J'19)
Step 1: Create a table of values
| x | -5 | -4 | -3 | -2 | -1 | 0 | 1 | 2 |
|---|---|---|---|---|---|---|---|---|
| p(x) | 6 | 0 | -4 | -6 | -6 | -4 | 0 | 6 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (-1.5, -6.25).
The graph is a parabola opening upwards with vertex at (-1.5, -6.25).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = -4 and x = 1.
From the table, we see p(x) = 0 when x = -4 and x = 1.
Step 4: Verify algebraically
x² + 3x - 4 = 0
(x + 4)(x - 1) = 0
x = -4 or x = 1
x² + 3x - 4 = 0
(x + 4)(x - 1) = 0
x = -4 or x = 1
∴ The zeros are x = -4 and x = 1
3
Draw the graph of the polynomial p(x) = 3x² + 2x - 1 on the graph paper. Find its zeros from the graph.
(J'15)
Step 1: Create a table of values
| x | -2 | -1 | -0.5 | 0 | 0.5 | 1 | 2 |
|---|---|---|---|---|---|---|---|
| p(x) | 7 | 0 | -1.25 | -1 | 0.75 | 4 | 15 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (-1/3, -4/3).
The graph is a parabola opening upwards with vertex at (-1/3, -4/3).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = -1 and x = 1/3.
From the table, we see p(x) = 0 when x = -1 and x = 1/3.
Step 4: Verify algebraically
3x² + 2x - 1 = 0
(3x - 1)(x + 1) = 0
x = 1/3 or x = -1
3x² + 2x - 1 = 0
(3x - 1)(x + 1) = 0
x = 1/3 or x = -1
∴ The zeros are x = -1 and x = 1/3
4
Draw the graph for the polynomial p(x) = x² - 3x + 2 and find the zeroes from the graph.
(M'16)
Step 1: Create a table of values
| x | -1 | 0 | 1 | 1.5 | 2 | 3 | 4 |
|---|---|---|---|---|---|---|---|
| p(x) | 6 | 2 | 0 | -0.25 | 0 | 2 | 6 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (1.5, -0.25).
The graph is a parabola opening upwards with vertex at (1.5, -0.25).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = 1 and x = 2.
From the table, we see p(x) = 0 when x = 1 and x = 2.
Step 4: Verify algebraically
x² - 3x + 2 = 0
(x - 1)(x - 2) = 0
x = 1 or x = 2
x² - 3x + 2 = 0
(x - 1)(x - 2) = 0
x = 1 or x = 2
∴ The zeros are x = 1 and x = 2
5
Draw the graph of the polynomial p(x) = x² - 5x + 4 on the graph paper. Find its zeros from the graph.
(J'16)
Step 1: Create a table of values
| x | -1 | 0 | 1 | 2 | 2.5 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|
| p(x) | 10 | 4 | 0 | -2 | -2.25 | -2 | 0 | 4 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (2.5, -2.25).
The graph is a parabola opening upwards with vertex at (2.5, -2.25).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = 1 and x = 4.
From the table, we see p(x) = 0 when x = 1 and x = 4.
Step 4: Verify algebraically
x² - 5x + 4 = 0
(x - 1)(x - 4) = 0
x = 1 or x = 4
x² - 5x + 4 = 0
(x - 1)(x - 4) = 0
x = 1 or x = 4
∴ The zeros are x = 1 and x = 4
6
On dividing x³ - 3x² + 5x - 7 by x² - 2x + 4, if the remainder is in the form of Ax + B, find the values of A and B.
(J'16)
Step 1: Perform polynomial division
x - 1
---------------
x² - 2x + 4 | x³ - 3x² + 5x - 7
x³ - 2x² + 4x
---------------
-x² + x - 7
-x² + 2x - 4
-----------
-x - 3
Step 2: Identify remainder
Remainder = -x - 3
Remainder = -x - 3
Step 3: Compare with Ax + B
-x - 3 = Ax + B
A = -1, B = -3
-x - 3 = Ax + B
A = -1, B = -3
∴ A = -1, B = -3
7
Divide 3x⁴ - 5x³ + 4x² + 3x - 5 by x² - 3 and verify the division algorithm.
(M'17)
Step 1: Perform polynomial division
3x² - 5x + 13
---------------
x² - 3 | 3x⁴ - 5x³ + 4x² + 3x - 5
3x⁴ + 0x³ - 9x²
---------------
-5x³ + 13x² + 3x
-5x³ + 0x² + 15x
---------------
13x² - 12x - 5
13x² + 0x - 39
---------------
-12x + 34
Step 2: Identify quotient and remainder
Quotient = 3x² - 5x + 13
Remainder = -12x + 34
Quotient = 3x² - 5x + 13
Remainder = -12x + 34
Step 3: Verify division algorithm
Division algorithm: Dividend = Divisor × Quotient + Remainder
(x² - 3)(3x² - 5x + 13) + (-12x + 34)
= 3x⁴ - 5x³ + 13x² - 9x² + 15x - 39 - 12x + 34
= 3x⁴ - 5x³ + 4x² + 3x - 5
This matches the original dividend.
Division algorithm: Dividend = Divisor × Quotient + Remainder
(x² - 3)(3x² - 5x + 13) + (-12x + 34)
= 3x⁴ - 5x³ + 13x² - 9x² + 15x - 39 - 12x + 34
= 3x⁴ - 5x³ + 4x² + 3x - 5
This matches the original dividend.
∴ Quotient = 3x² - 5x + 13, Remainder = -12x + 34
The division algorithm is verified.
The division algorithm is verified.
8
The perimeter of a right-angle triangle is 60 cm and its hypotenuse is 25 cm. Then find the remaining two sides.
(M'17)
Step 1: Set up equations
Let the sides be a, b, and c where c = 25 cm (hypotenuse)
Perimeter: a + b + c = 60 ⇒ a + b = 35
Pythagorean theorem: a² + b² = c² = 625
Let the sides be a, b, and c where c = 25 cm (hypotenuse)
Perimeter: a + b + c = 60 ⇒ a + b = 35
Pythagorean theorem: a² + b² = c² = 625
Step 2: Solve the system
From a + b = 35, we get b = 35 - a
Substitute in a² + b² = 625:
a² + (35 - a)² = 625
a² + 1225 - 70a + a² = 625
2a² - 70a + 1225 - 625 = 0
2a² - 70a + 600 = 0
Divide by 2: a² - 35a + 300 = 0
From a + b = 35, we get b = 35 - a
Substitute in a² + b² = 625:
a² + (35 - a)² = 625
a² + 1225 - 70a + a² = 625
2a² - 70a + 1225 - 625 = 0
2a² - 70a + 600 = 0
Divide by 2: a² - 35a + 300 = 0
Step 3: Solve the quadratic
a² - 35a + 300 = 0
(a - 15)(a - 20) = 0
a = 15 or a = 20
a² - 35a + 300 = 0
(a - 15)(a - 20) = 0
a = 15 or a = 20
Step 4: Find the corresponding sides
If a = 15, then b = 35 - 15 = 20
If a = 20, then b = 35 - 20 = 15
If a = 15, then b = 35 - 15 = 20
If a = 20, then b = 35 - 20 = 15
∴ The remaining two sides are 15 cm and 20 cm
9
Draw the graph of the polynomial p(x) = x² - 5x + 6 and find the zeros from the graph.
(M'17)
Step 1: Create a table of values
| x | -1 | 0 | 1 | 2 | 2.5 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|
| p(x) | 12 | 6 | 2 | 0 | -0.25 | 0 | 2 | 6 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (2.5, -0.25).
The graph is a parabola opening upwards with vertex at (2.5, -0.25).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = 2 and x = 3.
From the table, we see p(x) = 0 when x = 2 and x = 3.
Step 4: Verify algebraically
x² - 5x + 6 = 0
(x - 2)(x - 3) = 0
x = 2 or x = 3
x² - 5x + 6 = 0
(x - 2)(x - 3) = 0
x = 2 or x = 3
∴ The zeros are x = 2 and x = 3
10
Draw the graph of p(x) = x² - 2x - 8 and find the zeros of the polynomial from it.
(J'17)
Step 1: Create a table of values
| x | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|---|
| p(x) | 7 | 0 | -5 | -8 | -9 | -8 | -5 | 0 | 7 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (1, -9).
The graph is a parabola opening upwards with vertex at (1, -9).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = -2 and x = 4.
From the table, we see p(x) = 0 when x = -2 and x = 4.
Step 4: Verify algebraically
x² - 2x - 8 = 0
(x - 4)(x + 2) = 0
x = 4 or x = -2
x² - 2x - 8 = 0
(x - 4)(x + 2) = 0
x = 4 or x = -2
∴ The zeros are x = -2 and x = 4
11
Total number of pencils required are given by 4x⁴ + 2x³ - 2x² + 62x - 66.
If each box contains x² + 2x - 3 pencils, then find the number of boxes to be purchased.
(M'18)
Step 1: Perform polynomial division
We need to divide 4x⁴ + 2x³ - 2x² + 62x - 66 by x² + 2x - 3
We need to divide 4x⁴ + 2x³ - 2x² + 62x - 66 by x² + 2x - 3
Step 2: Division process
4x² - 6x + 22
---------------
x² + 2x - 3 | 4x⁴ + 2x³ - 2x² + 62x - 66
4x⁴ + 8x³ - 12x²
---------------
-6x³ + 10x² + 62x
-6x³ - 12x² + 18x
---------------
22x² + 44x - 66
22x² + 44x - 66
---------------
0
Step 3: Interpret the result
The quotient is 4x² - 6x + 22 and the remainder is 0.
The quotient is 4x² - 6x + 22 and the remainder is 0.
∴ Number of boxes to be purchased = 4x² - 6x + 22
12
Draw the graph of the polynomial p(x) = x² + x - 2 on the graph paper. Find its zeroes from the graph.
(J'18)
Step 1: Create a table of values
| x | -3 | -2 | -1 | -0.5 | 0 | 1 | 2 |
|---|---|---|---|---|---|---|---|
| p(x) | 4 | 0 | -2 | -2.25 | -2 | 0 | 4 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (-0.5, -2.25).
The graph is a parabola opening upwards with vertex at (-0.5, -2.25).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = -2 and x = 1.
From the table, we see p(x) = 0 when x = -2 and x = 1.
Step 4: Verify algebraically
x² + x - 2 = 0
(x + 2)(x - 1) = 0
x = -2 or x = 1
x² + x - 2 = 0
(x + 2)(x - 1) = 0
x = -2 or x = 1
∴ The zeros are x = -2 and x = 1
13
Draw the graph of the polynomial p(x) = x² - 7x + 12, then find its zeroes from the graph.
(M'19)
Step 1: Create a table of values
| x | 0 | 1 | 2 | 3 | 3.5 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|---|---|
| p(x) | 12 | 6 | 2 | 0 | -0.25 | 0 | 2 | 6 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (3.5, -0.25).
The graph is a parabola opening upwards with vertex at (3.5, -0.25).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = 3 and x = 4.
From the table, we see p(x) = 0 when x = 3 and x = 4.
Step 4: Verify algebraically
x² - 7x + 12 = 0
(x - 3)(x - 4) = 0
x = 3 or x = 4
x² - 7x + 12 = 0
(x - 3)(x - 4) = 0
x = 3 or x = 4
∴ The zeros are x = 3 and x = 4
14
Draw the graph of the polynomial p(x) = x² + 2x - 3 and find the zeroes of the polynomial from the graph.
(May 2022, Jun'23)
Step 1: Create a table of values
| x | -4 | -3 | -2 | -1 | 0 | 1 | 2 |
|---|---|---|---|---|---|---|---|
| p(x) | 5 | 0 | -3 | -4 | -3 | 0 | 5 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (-1, -4).
The graph is a parabola opening upwards with vertex at (-1, -4).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = -3 and x = 1.
From the table, we see p(x) = 0 when x = -3 and x = 1.
Step 4: Verify algebraically
x² + 2x - 3 = 0
(x + 3)(x - 1) = 0
x = -3 or x = 1
x² + 2x - 3 = 0
(x + 3)(x - 1) = 0
x = -3 or x = 1
∴ The zeros are x = -3 and x = 1
15
Draw the graph of the quadratic polynomial p(x) = x² - 4x + 3 and find the zeroes of the polynomial from the graph.
(Apr'23)
Step 1: Create a table of values
| x | -1 | 0 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|---|
| p(x) | 8 | 3 | 0 | -1 | 0 | 3 | 8 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (2, -1).
The graph is a parabola opening upwards with vertex at (2, -1).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = 1 and x = 3.
From the table, we see p(x) = 0 when x = 1 and x = 3.
Step 4: Verify algebraically
x² - 4x + 3 = 0
(x - 1)(x - 3) = 0
x = 1 or x = 3
x² - 4x + 3 = 0
(x - 1)(x - 3) = 0
x = 1 or x = 3
∴ The zeros are x = 1 and x = 3
16
Draw the graph of the polynomial p(x) = x² - x - 2 and find the zeros of the polynomial from the graph.
(Aug 2022)
Step 1: Create a table of values
| x | -2 | -1 | 0 | 0.5 | 1 | 2 | 3 |
|---|---|---|---|---|---|---|---|
| p(x) | 4 | 0 | -2 | -2.25 | -2 | 0 | 4 |
Step 2: Graph description
The graph is a parabola opening upwards with vertex at (0.5, -2.25).
The graph is a parabola opening upwards with vertex at (0.5, -2.25).
Step 3: Find zeros from the graph
From the table, we see p(x) = 0 when x = -1 and x = 2.
From the table, we see p(x) = 0 when x = -1 and x = 2.
Step 4: Verify algebraically
x² - x - 2 = 0
(x - 2)(x + 1) = 0
x = 2 or x = -1
x² - x - 2 = 0
(x - 2)(x + 1) = 0
x = 2 or x = -1
∴ The zeros are x = -1 and x = 2