Question

（x-1）²+ │y+1│=0 求2x²y-（2x²y-4x²y+5xy

Answer 1

因为（x-1)≥0│y+1│≥0

（x-1）²+ │y+1│=0

所以x=1,y=-1

2x²y-（2x²y-4x²y+5xy²) =4x2y-5xy2

=xy（4x-5y）

=-1*9

=-9