计算3x(1x2+2x3+3x4+……+99x100)的值是A97x98x99 B98x99x100 C99x100x1

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计算3x(1x2+2x3+3x4+……+99x100)的值是A97x98x99 B98x99x100 C99x100x101D100x101x102

1x2+2x3+3x4+…+n(n+1)=1x(1+1)+2x(2+1)+3x(3+1)+…n(n+1)=(1^2+2^2+3^2+…+n^2)+(1+2+3+…+n)=n(n+1)(2n+1)/6+n(n+1)/2=n(n+1)[(2n+1)+3]/6
3x(1x2+2x3+3x4+……+99x100)=3X99X100X202/6=99x100x101
选C

计算1x2+2x3+3x4+4x5+...+99x100 求1x2,2x3,3x4,4x5,……98x99,99x100的倒数和 1分之1x2+1分之2x3+1分之3x4.+1分之99x100 简便计算1/2+1/2x3+1/3x4+1/4x5+...+1/99x100 1/(1x2)+1/(2x3)+1/(3x4)+．．．．．．+1/(99x100)=?要计算过程． 1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101 1/1x2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100 1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果! 2/1x2+2/2x3+2/3x4+2/4x5+...+2/98x99+2/99x100 一定要帮我啊!(1/1x2)+(1/2x3)+(1/3x4)+(1/4x5)+.+(1/99x100)=? 已知x4+x3+x2+x+1=0，求x100+x99+x98+x97+x96的值．已知x1,x2,x3,x4成等比数列,且x1,x4是方程2x²+3x-1=0的两根,则x2+x3=