[3x的平方-(x+y)(y-x)][2(-x-y)(y-x)+2x的平方+3y的平方
=[3x²+(x+y)(x-y)][(x+y)(x-y)+2x²+3y²]
=[3x²+(x²-y²)][x²-y²)+2x²+3y²]
=[4x²-y²][3x²+2y²]
x=-1/2 y=3/2
=(4 * 1/4 - 9/4)(3* 1/4 + 2*9/4)
=-5/4 * 21/4
=-105/16