因为2x+5y-4=0
所以2x+5y=4
4x×32 Y
解:原式=22x ×25 Y
=2(2x+5 Y)
=24
=16
5x2-12xy+9y2-4x+4=0
解:4x2+ x2-12xy+9y2-4x+4=0
4x2-12xy+9y2+ x2-4x+4=0
(2x-3y)2+ (x-2)2=0
X=2
4-3 y=0
y= 3/4
xy=3/4×2
=1.5