问题
选择题
下列计算正确的是[ ]
A.xn(xn-x2+3)=x2n-xn+2+3xn
B.(2x+3y)(-4xy)=-8x2y-12xy2=-20xy
C.(-2xy2-4x2y)(-3xyz)=6x2y3+12x3y2
D.(xyz-7x2y+1)(-xz)=-x2yz2+7x3yz
答案
答案:A
下列计算正确的是[ ]
A.xn(xn-x2+3)=x2n-xn+2+3xn
B.(2x+3y)(-4xy)=-8x2y-12xy2=-20xy
C.(-2xy2-4x2y)(-3xyz)=6x2y3+12x3y2
D.(xyz-7x2y+1)(-xz)=-x2yz2+7x3yz
答案:A