Question

先化简，在求职。7x的平方y-xy-[3x的平方y-2(4xy的平方-2分之1xy)]-4x的平方y,其中x=-2分之1，y=3分之2

2分之1x-2（x-3分之1y的平方）+（-2分之3）x+3分之1y的平方，其中x=-2，y=3分之2

Answer 1

7X²Y-XY-[3X²Y-2(4XY²-0.5XY)]-4X²Y

=7X²Y-XY-(3X²Y-8XY²+XY)-4X²Y

=7X²Y-XY-3X²Y+8XY²-XY-4X²Y

=8XY²-2XY

=2XY(4Y-1)

=负九分之十

1/2X-2(X-1/3Y²)+(-3/2)X+1/3Y²

=1/2X-2X+2/3Y²-3/2X+1/3Y²

=3X+Y²

=负九分之五十

Answer 2