a+2b a-2b (a+2b)(a+2b) - (a-2b)(a-2b)
1) --------- - ----------- = ------------------------------------- =
a(a-2b) a(a+2b) a(a-2b)(a+2b)
a²+4ab+4b²-a²+4ab-4b² 8ab
= ------------------------------- = ------------------
a(a-2b)(a+2b) a(a-2b)(a+2b)
8ab a² 8a²b
2) ------------------ * --- = -------------------
a(a-2b)(a+2b) 1 a(a-2b)(a+2b)