Question

化简求值:2x的平方-[-3(-1/3x的平方-2/3xy)-2y的平方]-2(x平方-xy+2y平方)其中x=1,y=

Answer 1

2x²-[-3(-1/3x²-2/3xy)-2y²]-2(x²-xy+2y²)
=2x²-[x²+2xy-2y²]-2x²+2xy-4y²
=2x²-x²-2xy+2y²-2x²+2xy-4y²
=2x²-2x²-x²-2xy+2xy+2y²-4y²
=-x²-2y²
=-1²-2*1²
=-1-2
=-3
3a²-[4ab²-5(ab²+5/3a²)-3/2ab²]-a²b
=3a²-[4ab²-5ab²-25/3a²-3/2ab²]-a²b
=3a²-[-ab²-25/3a²-3/2ab²]-a²b
=3a²+ab²+25/3a²+3/2ab²-a²b
=3a²+25/3a²+ab²+3/2ab²-a²b
=34/3a²+5/2ab²-a²