1.已知x+3y=10,求(x^2-9y^2)/(x-3y)的值.

题目

1.已知x+3y=10,求(x^2-9y^2)/(x-3y)的值.
2.a^2(a-3)-(a-3)
3.如果 x^2-5x-6=(x+1)(x-m) 则m的值为
4.已知4a^2+4a+b^2-6b+10=0,则a^3b-ab^3=
5.如果m^2-4mn+4n^2=0,求(m^2+n^2)/mn的值

答案

1.(x^2-9y^2)/(x-3y) =(x-3y)(x+3y)/(x-3y) =x+3y =10 2.a^2(a-3)-(a-3) =(a^2-1)(a-3) =(a-1)(a+1)(a-3) 3.根据题意得:x^2-5x-6=(x+1)(x-6) 即:m=6 4.4a^2+4a+b^2-6b+10=0 (4a^2+4a+1)-1+(b^2-6b+9)-9+10=0 (2a+1)^...