若│x-2│与(y+二分之一)的平方互为相反数,求整式(x的平方y-3xy)-2(3x的平方y-2xy)的值
问题描述:
若│x-2│与(y+二分之一)的平方互为相反数,求整式(x的平方y-3xy)-2(3x的平方y-2xy)的值
答
│x-2│+(y+1/2)^2=0
│x-2│=0
(y+1/2)^2=0
x-2=0
x=2
y+1/2=0
y=-1/2
(x^2y-3xy)-2(3x^2y-2xy)
=-5x^2y+xy
=-5*2^2*(-1/2)+2*(-1/2)
=10-1
=9