若(x3+ax2-x2)·(-8x4)的运算结果中不含x的六次项,则a的值为___.
填空:
(1)(4x2-3x+6)·=___.
(2)a(2-a)-2(a+1)=___.
填空:
(1)(-5a4)·(-8ab2)=___.
(2)3x2y··(5xy2)=___.
(3)(2x-3y)=___.
(4)(-2ab)·(3a2-2ab-4b2)=___.
已知x+y=5,2x-y=1,则代数式xy(y+y2)-y2(xy-x)+2x(x-y2)的值为( )
A. 8 B. -28 C. -8 D. 无法确定
若p=x2y,则-x10y5·(-2x2y)3的计算结果是( )
A. -8p8 B. 8p8 C. -6p8 D. 6p8
若对于一切有理数x,等式x2(ax2+2x+4)=-3x4+2x3+4x2恒成立,则a的值是( )
A. -3 B. C. -6 D. -