Advanced Polynomial Operations

Multiplying and dividing polynomials

Advanced Polynomial Operations

Multiplying Polynomials

Use the distributive property repeatedly.

Example: (2x+3)(x24x+5)(2x + 3)(x^2 - 4x + 5)

Distribute 2x2x: 2x(x24x+5)=2x38x2+10x2x(x^2 - 4x + 5) = 2x^3 - 8x^2 + 10x

Distribute 33: 3(x24x+5)=3x212x+153(x^2 - 4x + 5) = 3x^2 - 12x + 15

Combine: 2x38x2+10x+3x212x+152x^3 - 8x^2 + 10x + 3x^2 - 12x + 15 =2x35x22x+15= 2x^3 - 5x^2 - 2x + 15

Long Division of Polynomials

Similar to long division with numbers.

Steps:

  1. Divide the leading terms
  2. Multiply and subtract
  3. Bring down the next term
  4. Repeat until done

Synthetic Division

A shortcut for dividing by (xc)(x - c).

Use only when divisor is in form (xc)(x - c).

Remainder Theorem

When polynomial P(x)P(x) is divided by (xc)(x - c): Remainder=P(c)\text{Remainder} = P(c)

📚 Practice Problems

1Problem 1easy

Question:

Add the polynomials: (3x² + 5x - 2) + (2x² - 3x + 7)

💡 Show Solution

Step 1: Group like terms: (3x² + 2x²) + (5x - 3x) + (-2 + 7)

Step 2: Combine coefficients: 5x² + 2x + 5

Answer: 5x² + 2x + 5

2Problem 2easy

Question:

Multiply: (x+5)(x2+3x+2)(x + 5)(x^2 + 3x + 2)

💡 Show Solution

Distribute each term in the first polynomial:

x(x2+3x+2)+5(x2+3x+2)x(x^2 + 3x + 2) + 5(x^2 + 3x + 2)

=x3+3x2+2x+5x2+15x+10= x^3 + 3x^2 + 2x + 5x^2 + 15x + 10

Combine like terms: =x3+8x2+17x+10= x^3 + 8x^2 + 17x + 10

Answer: x3+8x2+17x+10x^3 + 8x^2 + 17x + 10

3Problem 3easy

Question:

Multiply: (2x + 3)(x² - 4x + 5)

💡 Show Solution

Step 1: Distribute 2x to each term in the second polynomial: 2x(x²) + 2x(-4x) + 2x(5) = 2x³ - 8x² + 10x

Step 2: Distribute 3 to each term: 3(x²) + 3(-4x) + 3(5) = 3x² - 12x + 15

Step 3: Combine all terms: 2x³ - 8x² + 10x + 3x² - 12x + 15

Step 4: Combine like terms: 2x³ + (-8x² + 3x²) + (10x - 12x) + 15 2x³ - 5x² - 2x + 15

Answer: 2x³ - 5x² - 2x + 15

4Problem 4medium

Question:

Use the Remainder Theorem to find the remainder when P(x)=x34x2+6x2P(x) = x^3 - 4x^2 + 6x - 2 is divided by (x2)(x - 2)

💡 Show Solution

By the Remainder Theorem, the remainder when dividing by (x2)(x - 2) is P(2)P(2).

Evaluate P(2)P(2): P(2)=(2)34(2)2+6(2)2P(2) = (2)^3 - 4(2)^2 + 6(2) - 2 =816+122= 8 - 16 + 12 - 2 =2= 2

Answer: Remainder = 22

5Problem 5medium

Question:

Subtract: (4x³ + 2x² - 7x + 1) - (2x³ - 3x² + 5x - 4)

💡 Show Solution

Step 1: Distribute the negative sign: 4x³ + 2x² - 7x + 1 - 2x³ + 3x² - 5x + 4

Step 2: Group like terms: (4x³ - 2x³) + (2x² + 3x²) + (-7x - 5x) + (1 + 4)

Step 3: Combine: 2x³ + 5x² - 12x + 5

Step 4: Verify by plugging in x = 1: Original: (4 + 2 - 7 + 1) - (2 - 3 + 5 - 4) = 0 - 0 = 0 Result: 2 + 5 - 12 + 5 = 0 ✓

Answer: 2x³ + 5x² - 12x + 5

6Problem 6medium

Question:

Find the product: (x + 2)(x - 3)(x + 4)

💡 Show Solution

Step 1: Multiply the first two factors: (x + 2)(x - 3) = x² - 3x + 2x - 6 = x² - x - 6

Step 2: Multiply the result by the third factor: (x² - x - 6)(x + 4)

Step 3: Distribute x: x(x²) + x(-x) + x(-6) = x³ - x² - 6x

Step 4: Distribute 4: 4(x²) + 4(-x) + 4(-6) = 4x² - 4x - 24

Step 5: Combine all terms: x³ - x² - 6x + 4x² - 4x - 24 = x³ + 3x² - 10x - 24

Step 6: Verify by checking the constant term: Product of constants: 2 × (-3) × 4 = -24 ✓

Answer: x³ + 3x² - 10x - 24

7Problem 7hard

Question:

Divide using long division: (2x3+3x25x+1)÷(x+2)(2x^3 + 3x^2 - 5x + 1) \div (x + 2)

💡 Show Solution

Set up long division:

Step 1: 2x3÷x=2x22x^3 \div x = 2x^2 Multiply: 2x2(x+2)=2x3+4x22x^2(x + 2) = 2x^3 + 4x^2 Subtract: (2x3+3x2)(2x3+4x2)=x2(2x^3 + 3x^2) - (2x^3 + 4x^2) = -x^2

Step 2: x2÷x=x-x^2 \div x = -x Multiply: x(x+2)=x22x-x(x + 2) = -x^2 - 2x Subtract: (x25x)(x22x)=3x(-x^2 - 5x) - (-x^2 - 2x) = -3x

Step 3: 3x÷x=3-3x \div x = -3 Multiply: 3(x+2)=3x6-3(x + 2) = -3x - 6 Subtract: (3x+1)(3x6)=7(-3x + 1) - (-3x - 6) = 7

Answer: 2x2x3+7x+22x^2 - x - 3 + \frac{7}{x + 2}

8Problem 8hard

Question:

Expand and simplify: (2x - 1)³

💡 Show Solution

Step 1: Use the binomial expansion formula: (a + b)³ = a³ + 3a²b + 3ab² + b³

Step 2: Identify a = 2x and b = -1: (2x)³ + 3(2x)²(-1) + 3(2x)(-1)² + (-1)³

Step 3: Calculate each term: (2x)³ = 8x³ 3(2x)²(-1) = 3(4x²)(-1) = -12x² 3(2x)(-1)² = 3(2x)(1) = 6x (-1)³ = -1

Step 4: Combine: 8x³ - 12x² + 6x - 1

Step 5: Alternative method - multiply step by step: (2x - 1)² = 4x² - 4x + 1 (4x² - 4x + 1)(2x - 1) = 8x³ - 4x² - 8x² + 4x + 2x - 1 = 8x³ - 12x² + 6x - 1 ✓

Answer: 8x³ - 12x² + 6x - 1