题目

先化简 再求值【(y-2x)(-2x-y)-4(x-2y)的2次方}除以3y,其中x=-16分之3,y=-17分之3

提问时间：2020-08-07

答案

[(y-2x)(-2x-y)-4(x-2y)²]/(3y)
=[(2x-y)(2x+y)-4(x-2y)²]/(3y)
=[4x²-y²-4(x²-4xy+4y²)]/(3y)
=(4x²-y²-4x²+16xy-16y²)/(3y)
=(16xy-17y²)/(3y)
=16/3*x-17/3*y
=16/3*(-3/16)-17/3*(-3/17)
=-1+1=0