(1+2x)(1-2x) =12-(2x)2 =1-4x2 (b2+2a3)(2a3-b2) =(2a3+b2)(2a3-b2) =(2a3)2-(b2)2 =4a6-b4 (a-b)(a2+b2)(a4+b4)(a+b) =(a-b)(a+b)(a2+b2)(a4+b4) =(a2-b2)(a2+b2)(a4+b4) =(a4-b4)(a4+b4) =a8-b8