Question

1.(x/y-y/x)/(x+y) 2.(x的平方-4分之2x-x-2分之1）乘x-1分之x+2

Answer 1

1.原式=（x/y-y/x)*1/x+y=(x^2/xy-y^2/xy)*(1/x+y)=(x+y)(x-y)/xy*(1/x+y)=x-y/xy