已知（x+3）²+|x-y+10|=0,求5x²y-[2x²y-(3xy-xy²）-3x]-2xy²-y²的值.
问题描述：
已知（x+3）²+|x-y+10|=0,求5x²y-[2x²y-(3xy-xy²）-3x]-2xy²-y²的值.
答
x=-3,y=7
值为549
答
由前可得x=-3，x-y=-10,y=7可得后式的值
答
（x+3）²+|x-y+10|=0
（x+3）²=0 x=-3
|x-y+10|=0 y=7
5x²y-[2x²y-(3xy-xy²）-3x]-2xy²-y²
=5x²y-2x²y+3xy-xy²+3x-2xy²-y²
=3x²y-3xy²+3xy+3x-y²
=3*9*7+3*3*49-3*3*7-3*3-49
=189+441-72-49
=509
答
（x+3）²+|x-y+10|=0
所以呢：X+3=0 ---->X=-3
X-Y+10=0 ---->Y=7
接下来的呢：5x²y-[2x²y-(3xy-xy²）-3x]-2xy²-y²=509