先化简,再求值:(xy-x)/x^2-2xy+y^2*x^2-y^2/x^2,其中:x=-2,y=1/2_数学解答

先化简,再求值:(xy-x)/x^2-2xy+y^2*x^2-y^2/x^2,其中:x=-2,y=1/2

人气：157 ℃　时间：2020-05-13 16:47:29

解答

(xy-x)/(x^2-2xy+y^2)*(x^2-y^2)/x^2
=x(y-x)/(x-y)^2*(x+y)(x-y)/x^2
=-(x+y)/x
=-(-2+1/2)/(-2)
=-3/4