Polynomials & Factoring cheat sheet - grade 9-10

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Math Grade 9-10

Polynomials & Factoring Cheat Sheet

A printable reference covering polynomial vocabulary, operations, special products, factoring patterns, grouping, and the zero product property for grades 9-10.

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Polynomials are algebraic expressions made from terms with variables and whole-number exponents. This cheat sheet helps students recognize polynomial structure, combine like terms, multiply expressions, and factor efficiently. These skills are essential for simplifying algebra, solving equations, and preparing for quadratic functions. The main ideas include writing polynomials in standard form, using exponent rules, applying special product patterns, and choosing a factoring strategy. Important formulas include a2b2=(ab)(a+b)a^2-b^2=(a-b)(a+b), a2+2ab+b2=(a+b)2a^2+2ab+b^2=(a+b)^2, and a22ab+b2=(ab)2a^2-2ab+b^2=(a-b)^2. Factoring often means reversing multiplication, then using the zero product property to solve equations.

Key Facts

  • A polynomial in one variable can be written in standard form as anxn+an1xn1++a1x+a0a_nx^{n}+a_{n-1}x^{n-1}+\cdots+a_1x+a_0, where nn is a whole number and an0a_n\neq 0.
  • The degree of a polynomial is the greatest exponent of the variable, such as degree 44 for 7x43x2+97x^4-3x^2+9.
  • Like terms have the same variable part and exponent, so 5x22x2=3x25x^2-2x^2=3x^2.
  • When multiplying powers with the same base, add exponents: xmxn=xm+nx^m\cdot x^n=x^{m+n}.
  • The distributive property is a(b+c)=ab+aca(b+c)=ab+ac, and factoring uses the reverse form ab+ac=a(b+c)ab+ac=a(b+c).
  • The difference of squares pattern is a2b2=(ab)(a+b)a^2-b^2=(a-b)(a+b).
  • Perfect square trinomials factor as a2+2ab+b2=(a+b)2a^2+2ab+b^2=(a+b)^2 and a22ab+b2=(ab)2a^2-2ab+b^2=(a-b)^2.
  • The zero product property says if ab=0ab=0, then a=0a=0 or b=0b=0.

Vocabulary

Polynomial
A polynomial is an expression made of terms added or subtracted, where variable exponents are whole numbers.
Monomial
A monomial is a polynomial with one term, such as 6x36x^3.
Binomial
A binomial is a polynomial with two terms, such as x+5x+5.
Trinomial
A trinomial is a polynomial with three terms, such as x2+7x+10x^2+7x+10.
Greatest Common Factor
The greatest common factor is the largest factor shared by all terms in an expression.
Factor
A factor is a number or expression that is multiplied by another factor to make a product.

Common Mistakes to Avoid

  • Adding exponents when adding like terms is wrong because exponents stay the same during addition, so 3x2+4x2=7x23x^2+4x^2=7x^2, not 7x47x^4.
  • Forgetting to factor out the greatest common factor first can make factoring harder and may leave the answer incomplete.
  • Using the difference of squares on a sum is wrong because a2+b2a^2+b^2 does not factor as (a+b)(ab)(a+b)(a-b).
  • Dropping negative signs during grouping changes the expression, so x32x2+3x6x^3-2x^2+3x-6 must be grouped carefully as x2(x2)+3(x2)x^2(x-2)+3(x-2).
  • Setting only one factor equal to zero misses solutions because if (x4)(x+2)=0(x-4)(x+2)=0, both x4=0x-4=0 and x+2=0x+2=0 must be solved.

Practice Questions

  1. 1 Simplify and write in standard form: (3x25x+4)+(2x2+7x9)(3x^2-5x+4)+(2x^2+7x-9).
  2. 2 Multiply and simplify: (x+6)(x3)(x+6)(x-3).
  3. 3 Factor completely and solve: x29x+20=0x^2-9x+20=0.
  4. 4 Explain how you would decide whether to factor x2+10x+25x^2+10x+25 as a perfect square trinomial, and describe the pattern you are looking for.