Question

已知x=2+根号3,y=2-根号3,计算代数式(x+y/x-y-x-y/x+y)乘以(1/x^2-1/y^2)

Answer 1

即xy=2²-(√3)

=4-3=1

原式=[(x+y)²-(x-y)²]/(x+y)(x-y)*[-(x²-y²)/x²y²]

=(x²+2xy+y²-x²+2xy-y²)/(x+y)(x-y)*[-(x²-y²)/x²y²]

=-4xy/(x²-y²)*(x²-y²)/x²y²

=-4/xy

=-4/1

=-4