Question

先化简,在求值〔（xy+2)(xy-2)-2(x的平方y的平方-2）〕÷（xy),其中x=10,y=-1/25

Answer 1

=[(x^2y^2-4)-(2x^2y^2-4)]/xy

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

=x^2y^2/xy

=xy

=10*-1/25

=-2/5