Question

已知x=2+√3,y=2-√3,求(x-y分之x+y-x+y分之x-y)*(x2分之1-y2分之1)的值

Answer 1

x=2+√3,y=2-√3

那么：x+y=4

xy=4-3=1

x-y=2√3

(x-y分之x+y-x+y分之x-y)*(x2分之1-y2分之1)

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

=-(4xy)/x²y²

=-4/xy

=-4