1. Special Factoring Formulas
Section 5.5
Special Factoring Formulas

2. The Difference of Two Squares
a2 – b2 = (a + b)(a – b)
Examples:
1) 64x2 – 9 2) 49x2 – 81y2
3) 169x4 – 9y4 4) x6 – y8

3. The Sum and Difference of Two Cubes
a3 + b3= (a + b)(a 2 – ab + b2)
a3 - b3= (a - b)(a 2 + ab + b2)
Examples:
1) x ) z3 – 216
3) 27m3 - bn3 4) 125x3 + 27y3

4. General factoring guidelines
1. Factor out a GCF if possible.
2. If it’s a binomial, determine if it’s the sum or difference of two cubes or the difference of 2 squares. IF so, use the appropriate formula.
3. If it’s a trinomial, use the guess-and- check method from sections 5.3 and 5.4.
4. If it has 4 terms, try factoring by grouping.
5. Always double check to see if your factors can be factored further.