[(a³+2a²+4a)/(a³-8)-10/(a²+a-6)]/[1-21/(a²-4)]乘以(a+3)/(a-2)=[a(a²+2a+4)/(a-2)(a²+2a+4)-10/(a-2)(a+3)]/[(a²-25)/(a²-4)]×(a+3)/(a-2)=[a/(a-2)-10/(a-2)(a+3...