已知A=2x²+3xy-y²,B=-1/2xy,C=1/8x³y³-1/4x²y^4.求:2AB²-C

2AB²-C
=2(2x²+3xy-y²)(-1/2xy)²-(1/8x³y³-1/4x²y^4)
=2(2x²+3xy-y²)(x²y²)/4-(1/8x³y³-1/4x²y^4)
=x^4y^2+3/2*x^3y^3-1/2*x^2y^4-(1/8x³y³-1/4x²y^4)
=x^4y^2+11/8*x^3y^3-1/4*x^2y^4
如仍有疑惑,欢迎追问.祝：�����������Ҳ�ҵ��ˣ��ɣ��������还可以提取一个x^2y^2/8出来最后是x^2y^2(8x^2+11xy-2y^2)/8至于里面的，系数是8,11,-2已经无法分解了。