已知a/a-b=2,求a^3-4a^2b-5ab^2/a^3-6a^2b+5ab^2的值
问题描述：
已知a/a-b=2,求a^3-4a^2b-5ab^2/a^3-6a^2b+5ab^2的值
答
a/a-b = 2所以 a = 2b
a^3-4a^2b-5ab^2/a^3-6a^2b+5ab^2
=a(a^2 - 4ab - 5b^2)/a(a^2 - 6ab + 5b^2)
=(a - 5b)(a +b)/(a - 5b)(a - b)
= a + b/a - b
=3b/b
=3