若x^2+y^2=8.25,x-y=1.5,则(xy)^4=

问题描述:

若x^2+y^2=8.25,x-y=1.5,则(xy)^4=

x-y=1.5
(x-y)^2=2.25
2xy
=(x^2+y^2)-(x-y)^2
=8.25-2.25
=6
xy=6/2=3
(xy)^4=81