6 2 6 2 6 - 2*(х+3) 6-2х-6 -2х
---------- - ------- = ---------- - -------- = --------------------- = ------------ = --------------
х²+3х х х (х+3) х х (х+3) х (х+3) х (х+3)
5b a²-b² 5b (a-b)(a+b) a+b
--------- * --------- = -------- * -------------------- = -------------
a²-ab 10b² a(a-b) 10b² 2ab