Question

1、若x^2-9=0,则(x^2-5x+6)/(x-3)的值为_____;

Answer 1

1、x?-9=0,x=-3（x=3不符题意,舍去）.那么：(x?-5x+6)/(x-3)=(x-2)(x-3)/(x-3)=x-2=-3-2=-5

2、原式=12/[(m+3)(m-3)]-2/(m-3)=(12-2m-6)/[(m+3)(m-3)]=-2(m-3)/[(m+3)(m-3)]=-2/(m+3)

3、原式=(a?-b?-a?+b?)/[a(a-b)]=0

4、原式=(a?-b?+2b?)/(a+b)=(a?+b?)/(a+b)

5、原式=(x-2)/(x-3)-2=(x-2-2x+6)/(x-3)=(4-x)/(x-3)