S=1+2x+3x2+4x3+…+nxn-1(x≠0且x≠1)= ___ .
S=1+2x+3x2+4x3+…+nxn-1(x≠0且x≠1)= ___ .
求和Sn=x+2x2+3x3+…+nxn(x≠0).
请问S=1+2X+3X2+4X3+.+nXn-1的解法
求和:Sn=1+2x+3x2+…+nxn-1.
1x1+2x2+3x3+----+nxn=?
化简并求值:3x3-[x3+(6x2-7x)]-2(x3-3x2-4x)其中x=-1.
1x1!+2x2!+3x3!+4x4!.nxn!
已知1+x+x2+x3=0,求x+x2+x3+…+x2004的值.
若1+x+x2+x3=0,求x+x2+x3+…+x2000的值.
证明:(x3+5x2+4x-1)-(-x2-3x+2x3-3)+(8-7x-6x2+x3)的值与x无关.
已知x2+x-1=0,求2x3+3x2-x的值.
若x2+x-1=0,则2x3+3x2-x( )