已知x、y满足

更新时间2018-03-18 15:42:26

（x+2y）（x-2y）=-5（y^2-6/5）,2x(y-1)+4(0.5x-1)=0

(1)(x-y)^2

(2)x^4+y^4-x^2*y^2

（x+2y）（x-2y）=-5（y^2-6/5）

x^2-4y^2=-5y^2+6

x^2+y^2=6

2x(y-1)+4(0.5x-1)=0

2xy-2x+2x-4=0

2xy=4

xy=2

(x-y)^2=x^2+y^2-2xy=6-4=2

x^4+y^4-x^2y^2

=(x^2+y^2)-3x^2y^2

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

=6^2-3*2^2

=36-12

=24