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

问题描述:

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

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)...