x+y=-6,xy=2,则2x^2+2y^2=?_数学解答

x+y=-6,xy=2,则2x^2+2y^2=?

人气：246 ℃　时间：2020-03-28 15:54:01

解答

2x^2+2y^2
=2(x^2+y^2+2xy-2xy)
=2((x^2+y^2+2xy)-2xy)
=2((x+y)^2-2xy)
=2((-6)^2-2*2)
=2(36-4)
=64