先化简,再求值：x^2-3xy/x^2-6xy+9y^2,其实x=-1,y=2/3.a^2-2ab+b^2/b-a m^2-2m+_数学解答

先化简,再求值：x^2-3xy/x^2-6xy+9y^2,其实x=-1,y=2/3.a^2-2ab+b^2/b-a m^2-2m+1/m-1+4-m^2/m+2

人气：270 ℃　时间：2019-11-08 13:13:33

解答

1.x^2-3xy/x^2-6xy+9y^2=（x-3y）²-3y/x将x=-1,y=2/3代入得：（-1-3×2/3）²-3×2/3÷（-1）=112.a^2-2ab+b^2/b-a=（a-b）²÷（b-a）=b-a3.m^2-2m+1/m-1+4-m^2/m+2=（m-1）²÷（m-1）...