x[x-1]-[x^2-y]=2,3x^2加3y^2/2-3xy等于多少_数学解答

x[x-1]-[x^2-y]=2,3x^2加3y^2/2-3xy等于多少

人气：496 ℃　时间：2020-04-13 05:13:17

解答

x[x-1]-[x^2-y]=2
x^2-x-x^2+y=2
y-x=2
x-y=-2
(3x^2+3y^2)/2-3xy
=(3x^2+3y^2-6xy)/2
=3(x-y)^2/2
=3*(-2)^2/2
=6