（1）x³y+2x²y²+xy³=xy(x^2+2xy+y^2)=xy*(x+y)^2
而(x+y)^2=25,x²+y²=13,xy=6
所以xy*(x+y)^2=150
（2）a²b+ab²=ab(a+b)=40*13=520
(3)202²-54²+256×352
=(202+54)*(202-54)+256×352
=256*148+256×352
=256*500
=128000
(4)|x+2y-1|+（2x-y-2）² =0
则x+2y=1
2x-y=2
（2x-y）² -2（2x-y)+(x+2y）²
=2^2-2*2+1^2
=1