1x3+2x4+3x5+4x6……+100x102=?
1/2x4十1/4x6十…十1/100X102
X1+X2+X3+X4+X5+X6+X7=2010,X1+X2=X3,X2+X3=X4,X3+X4=X5,X4+X5=X
1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101
1/1X2+1/2X3+1/3X4+1/4X5+1/5X6……1/2007X2008
计算(1+1/1x3)(1+1/2x4)(1+1/3x5)(1+/4x6)……(1+/11×13)
1x2/1+2x3/1+3x4/1+4x5/1+5x6/1+6x7/1
1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+......1/2008x2009
1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7
(2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(19X21)==?
打点计时器求加速度的逐差法是怎么推导的?就是a=<(x6+x5+x4)-(x3+x2+x1)>╱9t∧2 这个公式怎么来
x8+x7+x6+x5+x4+x3+x2+x+1因式分解
1x2+2x3+3x4+4x5+……+10x11