1. Special Factoring Formulas & a General Review of Factoring
Section 5.5
Special Factoring Formulas &
a General Review of Factoring

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

3. 2. The Sum and Difference of Two Cubes
a3 + b3= (a + b)(a 2 – ab + b2)
a3 - b3= (a - b)(a 2 + ab + b2)
1) x ) z3 – 216
3) 81m3 - 3n ) 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 Reverse FOIL method from section If it has 4 terms, factor by grouping. 5. Always double check to see if your factors can be factored further!