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Polynomials and Factoring

Factor polynomials, perform polynomial arithmetic, understand the relationship between factors and zeros, and use the Remainder Theorem.

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Polynomials and Factoring on the SAT

What Is a Polynomial?

A polynomial is an expression with variables and coefficients using only addition, subtraction, multiplication, and non-negative integer exponents.

P(x)=anxn+an−1xn−1+⋯+a1x+a0P(x) = a_nx^n + a_{n-1}x^{n-1} + \cdots + a_1x + a_0

  • Degree: The highest power of the variable
  • Leading coefficient: The coefficient of the highest-degree term
  • Constant term: The term with no variable (a0a_0)

Types of Polynomials

DegreeNameExample
0Constant55
1Linear3x+23x + 2
2Quadraticx2−4x+1x^2 - 4x + 1
3Cubic2x3+x−72x^3 + x - 7
4Quarticx4−3x2+1x^4 - 3x^2 + 1

Factoring Techniques

1. Greatest Common Factor (GCF)

6x3+9x2=3x2(2x+3)6x^3 + 9x^2 = 3x^2(2x + 3)

2. Difference of Squares

a2−b2=(a+b)(a−b)a^2 - b^2 = (a + b)(a - b) Example: x2−25=(x+5)(x−5)x^2 - 25 = (x+5)(x-5)

3. Perfect Square Trinomials

a2+2ab+b2=(a+b)2a^2 + 2ab + b^2 = (a + b)^2 a2−2ab+b2=(a−b)2a^2 - 2ab + b^2 = (a - b)^2 Example: x2+10x+25=(x+5)2x^2 + 10x + 25 = (x+5)^2

4. Trinomial Factoring (x2+bx+cx^2 + bx + c)

Find two numbers that multiply to cc and add to bb. Example: x2+7x+12=(x+3)(x+4)x^2 + 7x + 12 = (x+3)(x+4)

5. Trinomial Factoring (ax2+bx+cax^2 + bx + c, a≠1a \neq 1)

Use the AC method or trial and error. Example: 2x2+7x+3=(2x+1)(x+3)2x^2 + 7x + 3 = (2x+1)(x+3)

6. Sum and Difference of Cubes

a3+b3=(a+b)(a2−ab+b2)a^3 + b^3 = (a + b)(a^2 - ab + b^2) a3−b3=(a−b)(a2+ab+b2)a^3 - b^3 = (a - b)(a^2 + ab + b^2)

7. Factor by Grouping

x3+3x2+2x+6=x2(x+3)+2(x+3)=(x2+2)(x+3)x^3 + 3x^2 + 2x + 6 = x^2(x+3) + 2(x+3) = (x^2+2)(x+3)


Polynomial Operations

Addition/Subtraction

Combine like terms (same variable, same exponent).

Multiplication

Use FOIL for binomials, or distribute each term. (2x+3)(x−4)=2x2−8x+3x−12=2x2−5x−12(2x + 3)(x - 4) = 2x^2 - 8x + 3x - 12 = 2x^2 - 5x - 12

Division

Polynomial long division or synthetic division (for dividing by x−cx - c).


Remainder Theorem

When polynomial P(x)P(x) is divided by (x−c)(x - c), the remainder is P(c)P(c).

Example: If P(x)=x3−2x+1P(x) = x^3 - 2x + 1, the remainder when divided by (x−3)(x - 3) is: P(3)=27−6+1=22P(3) = 27 - 6 + 1 = 22


Factor Theorem

(x−c)(x - c) is a factor of P(x)P(x) if and only if P(c)=0P(c) = 0.

Example: Is (x−2)(x - 2) a factor of x3−4x2+x+6x^3 - 4x^2 + x + 6? P(2)=8−16+2+6=0P(2) = 8 - 16 + 2 + 6 = 0 → Yes!


SAT Question Types

Type 1: Factor a Polynomial

"Factor x2−5x−6x^2 - 5x - 6" → (x−6)(x+1)(x-6)(x+1)

Type 2: Find Zeros from Factored Form

"If f(x)=(x−2)(x+3)(x−5)f(x) = (x-2)(x+3)(x-5), what are the zeros?" → x=2,−3,5x = 2, -3, 5

Type 3: Polynomial Division

"What is the remainder when x3+2x−5x^3 + 2x - 5 is divided by x−1x - 1?" P(1)=1+2−5=−2P(1) = 1 + 2 - 5 = -2 (use the Remainder Theorem!)

Type 4: Equivalent Expressions

"Which expression is equivalent to (x+2)3(x+2)^3?" =x3+3(x2)(2)+3(x)(4)+8=x3+6x2+12x+8= x^3 + 3(x^2)(2) + 3(x)(4) + 8 = x^3 + 6x^2 + 12x + 8


Common SAT Mistakes

  1. Sign errors when factoring — double-check by FOILing your answer
  2. Forgetting the GCF before trying other methods
  3. Confusing (x+3)2(x+3)^2 with x2+9x^2 + 9 — it's x2+6x+9x^2 + 6x + 9!
  4. Not using the Remainder Theorem — much faster than long division
  5. Dropping terms when subtracting polynomials — distribute the negative sign

📚 Practice Problems

1Problem 1easy

❓ Question:

Expand: (x+6)(x−2)(x + 6)(x - 2)

💡 Show Solution

Solution:

Use FOIL (First, Outer, Inner, Last):

F: x⋅x=x2x \cdot x = x^2 O: x⋅(−2)=−2xx \cdot (-2) = -2x I: 6⋅x=6x6 \cdot x = 6x L: 6⋅(−2)=−126 \cdot (-2) = -12

Combine: x2−2x+6x−12x^2 - 2x + 6x - 12 =x2+4x−12= x^2 + 4x - 12

Answer: x2+4x−12x^2 + 4x - 12

SAT Tip: Don't forget to combine like terms after FOIL-ing!

2Problem 2medium

❓ Question:

Factor completely: x2−49x^2 - 49

💡 Show Solution

Solution:

Recognize difference of squares pattern: a2−b2=(a+b)(a−b)a^2 - b^2 = (a+b)(a-b)

Here: x2−49=x2−72x^2 - 49 = x^2 - 7^2

Factor: =(x+7)(x−7)= (x + 7)(x - 7)

Answer: (x+7)(x−7)(x + 7)(x - 7)

Check: (x+7)(x−7)=x2−7x+7x−49=x2−49(x+7)(x-7) = x^2 - 7x + 7x - 49 = x^2 - 49 ✓

SAT Tip: Difference of squares is common! Memorize a2−b2=(a+b)(a−b)a^2 - b^2 = (a+b)(a-b)

3Problem 3hard

❓ Question:

Which is equivalent to (2x−3)2(2x - 3)^2?

A) 4x2−94x^2 - 9 B) 4x2+94x^2 + 9 C) 4x2−12x+94x^2 - 12x + 9 D) 4x2+12x+94x^2 + 12x + 9

💡 Show Solution

Solution:

Use square of a difference pattern: (a−b)2=a2−2ab+b2(a - b)^2 = a^2 - 2ab + b^2

Here: a=2xa = 2x, b=3b = 3

(2x)2=4x2(2x)^2 = 4x^2 −2(2x)(3)=−12x-2(2x)(3) = -12x 32=93^2 = 9

Result: 4x2−12x+94x^2 - 12x + 9

Answer: C

Common trap: A is (2x+3)(2x−3)(2x+3)(2x-3) (difference of squares, not square!)

SAT Tip: (a−b)2(a-b)^2 has THREE terms, not two! Don't forget the middle term.

4Problem 4easy

❓ Question:

Factor completely: 3x2−123x^2 - 12

💡 Show Solution

Step 1: Factor out the GCF first: 3x2−12=3(x2−4)3x^2 - 12 = 3(x^2 - 4)

Step 2: Recognize the difference of squares: 3(x2−4)=3(x+2)(x−2)3(x^2 - 4) = 3(x + 2)(x - 2)

Answer: 3(x+2)(x−2)3(x+2)(x-2)

Key: Always look for a GCF first!

5Problem 5easy

❓ Question:

Factor completely: 3x2−123x^2 - 12

💡 Show Solution

Step 1: Factor out the GCF first: 3x2−12=3(x2−4)3x^2 - 12 = 3(x^2 - 4)

Step 2: Recognize the difference of squares: 3(x2−4)=3(x+2)(x−2)3(x^2 - 4) = 3(x + 2)(x - 2)

Answer: 3(x+2)(x−2)3(x+2)(x-2)

Key: Always look for a GCF first!

6Problem 6medium

❓ Question:

Factor: 2x2+7x+32x^2 + 7x + 3

💡 Show Solution

AC Method: a⋅c=2⋅3=6a \cdot c = 2 \cdot 3 = 6. Find two numbers that multiply to 6 and add to 7: 6 and 1.

Rewrite middle term: 2x2+6x+x+32x^2 + 6x + x + 3

Factor by grouping: 2x(x+3)+1(x+3)2x(x + 3) + 1(x + 3) (2x+1)(x+3)(2x + 1)(x + 3)

Check: (2x+1)(x+3)=2x2+6x+x+3=2x2+7x+3(2x+1)(x+3) = 2x^2 + 6x + x + 3 = 2x^2 + 7x + 3 ✓

Answer: (2x+1)(x+3)(2x+1)(x+3)

7Problem 7medium

❓ Question:

Factor: 2x2+7x+32x^2 + 7x + 3

💡 Show Solution

AC Method: a⋅c=2⋅3=6a \cdot c = 2 \cdot 3 = 6. Find two numbers that multiply to 6 and add to 7: 6 and 1.

Rewrite middle term: 2x2+6x+x+32x^2 + 6x + x + 3

Factor by grouping: 2x(x+3)+1(x+3)2x(x + 3) + 1(x + 3) (2x+1)(x+3)(2x + 1)(x + 3)

Check: (2x+1)(x+3)=2x2+6x+x+3=2x2+7x+3(2x+1)(x+3) = 2x^2 + 6x + x + 3 = 2x^2 + 7x + 3 ✓

Answer: (2x+1)(x+3)(2x+1)(x+3)

8Problem 8medium

❓ Question:

What is the remainder when P(x)=2x3−x2+3x−7P(x) = 2x^3 - x^2 + 3x - 7 is divided by (x−2)(x - 2)?

💡 Show Solution

Use the Remainder Theorem: The remainder when P(x)P(x) is divided by (x−c)(x - c) is P(c)P(c).

Here c=2c = 2: P(2)=2(2)3−(2)2+3(2)−7P(2) = 2(2)^3 - (2)^2 + 3(2) - 7 =2(8)−4+6−7= 2(8) - 4 + 6 - 7 =16−4+6−7= 16 - 4 + 6 - 7 =11= 11

Answer: The remainder is 11.

SAT Tip: The Remainder Theorem saves enormous time compared to polynomial long division!

9Problem 9medium

❓ Question:

What is the remainder when P(x)=2x3−x2+3x−7P(x) = 2x^3 - x^2 + 3x - 7 is divided by (x−2)(x - 2)?

💡 Show Solution

Use the Remainder Theorem: The remainder when P(x)P(x) is divided by (x−c)(x - c) is P(c)P(c).

Here c=2c = 2: P(2)=2(2)3−(2)2+3(2)−7P(2) = 2(2)^3 - (2)^2 + 3(2) - 7 =2(8)−4+6−7= 2(8) - 4 + 6 - 7 =16−4+6−7= 16 - 4 + 6 - 7 =11= 11

Answer: The remainder is 11.

SAT Tip: The Remainder Theorem saves enormous time compared to polynomial long division!

10Problem 10hard

❓ Question:

If f(x)=x3−6x2+11x−6f(x) = x^3 - 6x^2 + 11x - 6 and f(1)=0f(1) = 0, factor f(x)f(x) completely.

💡 Show Solution

Step 1: Since f(1)=0f(1) = 0, by the Factor Theorem, (x−1)(x - 1) is a factor.

Step 2: Divide x3−6x2+11x−6x^3 - 6x^2 + 11x - 6 by (x−1)(x - 1) using synthetic division:

1∣1−611−61 | 1 \quad -6 \quad 11 \quad -6 ∣1−56\quad | \quad 1 \quad -5 \quad 6 1−560\quad 1 \quad -5 \quad 6 \quad 0

Quotient: x2−5x+6x^2 - 5x + 6

Step 3: Factor the quadratic: x2−5x+6=(x−2)(x−3)x^2 - 5x + 6 = (x - 2)(x - 3)

Answer: f(x)=(x−1)(x−2)(x−3)f(x) = (x-1)(x-2)(x-3)

The zeros are x=1,2,3x = 1, 2, 3.

11Problem 11hard

❓ Question:

If f(x)=x3−6x2+11x−6f(x) = x^3 - 6x^2 + 11x - 6 and f(1)=0f(1) = 0, factor f(x)f(x) completely.

💡 Show Solution

Step 1: Since f(1)=0f(1) = 0, by the Factor Theorem, (x−1)(x - 1) is a factor.

Step 2: Divide x3−6x2+11x−6x^3 - 6x^2 + 11x - 6 by (x−1)(x - 1) using synthetic division:

1∣1−611−61 | 1 \quad -6 \quad 11 \quad -6 ∣1−56\quad | \quad 1 \quad -5 \quad 6 1−560\quad 1 \quad -5 \quad 6 \quad 0

Quotient: x2−5x+6x^2 - 5x + 6

Step 3: Factor the quadratic: x2−5x+6=(x−2)(x−3)x^2 - 5x + 6 = (x - 2)(x - 3)

Answer: f(x)=(x−1)(x−2)(x−3)f(x) = (x-1)(x-2)(x-3)

The zeros are x=1,2,3x = 1, 2, 3.

12Problem 12expert

❓ Question:

Which polynomial has zeros at x=−1x = -1, x=2x = 2, and x=4x = 4, and passes through the point (0,−16)(0, -16)?

💡 Show Solution

Step 1: Write the general form using the zeros: f(x)=a(x+1)(x−2)(x−4)f(x) = a(x + 1)(x - 2)(x - 4)

Step 2: Use the point (0,−16)(0, -16) to find aa: f(0)=a(0+1)(0−2)(0−4)=a(1)(−2)(−4)=8af(0) = a(0 + 1)(0 - 2)(0 - 4) = a(1)(-2)(-4) = 8a −16=8a-16 = 8a a=−2a = -2

Step 3: Write the final polynomial: f(x)=−2(x+1)(x−2)(x−4)f(x) = -2(x+1)(x-2)(x-4)

Check: f(0)=−2(1)(−2)(−4)=−2(8)=−16f(0) = -2(1)(-2)(-4) = -2(8) = -16 ✓

Answer: f(x)=−2(x+1)(x−2)(x−4)f(x) = -2(x+1)(x-2)(x-4)

Expanded: f(x)=−2x3+10x2−4x−16f(x) = -2x^3 + 10x^2 - 4x - 16

13Problem 13expert

❓ Question:

Which polynomial has zeros at x=−1x = -1, x=2x = 2, and x=4x = 4, and passes through the point (0,−16)(0, -16)?

💡 Show Solution

Step 1: Write the general form using the zeros: f(x)=a(x+1)(x−2)(x−4)f(x) = a(x + 1)(x - 2)(x - 4)

Step 2: Use the point (0,−16)(0, -16) to find aa: f(0)=a(0+1)(0−2)(0−4)=a(1)(−2)(−4)=8af(0) = a(0 + 1)(0 - 2)(0 - 4) = a(1)(-2)(-4) = 8a −16=8a-16 = 8a a=−2a = -2

Step 3: Write the final polynomial: f(x)=−2(x+1)(x−2)(x−4)f(x) = -2(x+1)(x-2)(x-4)

Check: f(0)=−2(1)(−2)(−4)=−2(8)=−16f(0) = -2(1)(-2)(-4) = -2(8) = -16 ✓

Answer: f(x)=−2(x+1)(x−2)(x−4)f(x) = -2(x+1)(x-2)(x-4)

Expanded: f(x)=−2x3+10x2−4x−16f(x) = -2x^3 + 10x^2 - 4x - 16

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📌 Related Topics in Advanced Math

❓ Frequently Asked Questions

What is Polynomials and Factoring?▾
Factor polynomials, perform polynomial arithmetic, understand the relationship between factors and zeros, and use the Remainder Theorem.
How can I study Polynomials and Factoring effectively?▾
Start by reading the study notes and working through the examples on this page. Then use the flashcards to test your recall. Practice with the 13 problems provided, checking solutions as you go. Regular review and active practice are key to retention.
Is this Polynomials and Factoring study guide free?▾
Yes — all study notes, flashcards, and practice problems for Polynomials and Factoring on Study Mondo are free to access. No account is needed.
What course covers Polynomials and Factoring?▾
Polynomials and Factoring is part of the SAT Prep course on Study Mondo, specifically in the Advanced Math section. You can explore the full course for more related topics and practice resources.
Are there practice problems for Polynomials and Factoring?▾
Yes, this page includes 13 practice problems with detailed solutions. Each problem includes a step-by-step explanation to help you understand the approach.