1（3X^2+2XY-1/2X)-(2X^2-XY+x)

(3x^2+2xy-1/2x)-(2x^2-xy+x)
=3x^2+2xy-1/2x-2x^2+xy-x
=3x^2-2x^2+2xy+xy-1/2x-x
=x^2+3xy-3/2x
（1/2xy+y^2+1)+(x^2-1/2xy-2y^2-1)
=1/2xy-1/2xy+y^2+1+x^2-2y^2-1
=x^2-y^2
.-(x^2y+3xy-4)+3(x^2y-xy+2)
=-x^2y-3xy+4+3x^2y-3xy+6
=+2x^2y-6xy+10
-1/4(2k^3+4k^2-28)+1/2(k^3-2k^2+4k)
=-1/2k^3-k^2+7+1/2k^3-k^2+2k
=(1/2k^3-1/2k^3)-(k^2+k^2)+2k+7
=-2k^2+2k+7

解什么，求什么？化简？

1（3X^2+2XY-1/2X)-(2X^2-XY+x)
=3X²-2X ²+2XY+XY-1/2X-X
=X²+3XY-3X/2
2 (1/2XY+Y^2+1)+(X^2-1/2XY-2Y^2-1)
=1/2XY-1/2XY+Y²-2Y²+X²+1-1
=X²-Y²...

1（3X^2+2XY-1/2X)-(2X^2-XY+x)
解，得：
==（3X^2+2XY-1/2X)-(2X^2-XY+x)
==3x^2+2xy-1/2x-2x^2+xy-x
==3x^2-2x^2+2xy+xy-1/2x-x
==x^2+3xy-3/2x
2 (1/2XY+Y^2+1)+(X^2-1/2XY-2Y^2-1)
解，得：