先化简 再求值:[4(xy-1)^2-(xy+2)(2-xy)]1/4xy,其中x=-2,y=1/5

先化简 再求值:[4(xy-1)^2-(xy+2)(2-xy)]1/4xy,其中x=-2,y=1/5
先化简 再求值:[4(xy-1)^2-(xy+2)(2-xy)]1/4xy,其中x=-2,y=1/5

先化简 再求值:[4(xy-1)^2-(xy+2)(2-xy)]1/4xy,其中x=-2,y=1/5
[4(xy-1)^2-(xy+2)(2-xy)]1/4xy
=[4(xy-1)^2 +(xy+2)(xy-2)]1/4xy
=[4(xy)²-8(xy)+4+(xy)²-4]÷(4xy)
=[5(xy)²-8(xy)]÷(4xy)
=(5xy-8)/4
已知x=-2,y=1/5,那么：xy=-2/5
所以：原式=(5xy-8)/4=[5*(-2/5)-8]/4=(-10)/4=-5/2