作业帮用裂项法求值1/1x2x3 + 1/2x3x4 +1/3x4x5 + … + 1/n(n+1)(n+2)1/1x3 + 1/2x4 + 1/3x5 … + 1/n(n+2)
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用裂项法求值1/1x2x3 + 1/2x3x4 +1/3x4x5 + … + 1/n(n+1)(n+2)1/1x3 + 1/2x4 + 1/3x5 … + 1/n(n+2)
用裂项法求值
1/1x2x3 + 1/2x3x4 +1/3x4x5 + … + 1/n(n+1)(n+2)
1/1x3 + 1/2x4 + 1/3x5 … + 1/n(n+2)
用裂项法求值1/1x2x3 + 1/2x3x4 +1/3x4x5 + … + 1/n(n+1)(n+2)1/1x3 + 1/2x4 + 1/3x5 … + 1/n(n+2)
1/n(n+1)(n+2)=[1/n(n+1)-1/(n+1)(n+2)]/2
1/1x2x3 + 1/2x3x4 +1/3x4x5 + … + 1/n(n+1)(n+2)
=[和1/n(n+1)-和1/(n+1)(n+2)]/2
=[1-1/(n+1)-1/2+1/(n+2)]/2
=1/4-1/2(n+1)(n+2)
1/n(n+2)=[1/n-1/(n+2)]/2
1/1x3 + 1/2x4 + 1/3x5 … + 1/n(n+2)
=[1+1/2-1/(n+1)-1/(n+2)]/2
=3/4-1/2(n+1)-1/2(n+2)
1/n(n+2)=1/2(1/n- 1/(n+2))
1/n(n+1)(n+2) =1/2(1/n(n+1)-1/(n+1)(n+2))
不要误会，我可不是抄楼上的！
1x2x3,x100
1x2x3+2x3x4+...+nxx=?
1x2=1/3x(1x2x3-0x1x2)2x3=1/3x(2x3x4-1x2x3)3x4=1/3x(3x4x5-2x3x4)求1x2x3+2x3x4+3x4x5+...+7x8x9=?
编程实现:1x2x3...x100
用裂项法求值1/1x2x3 + 1/2x3x4 +1/3x4x5 + … + 1/n(n+1)(n+2)1/1x3 + 1/2x4 + 1/3x5 … + 1/n(n+2)
1/1x2x3+1/2x3x4+.+1/98x99x100 .
1/1X2X3+1/2X3x4+…+1/48X49X50
1X2X3+2X3X4+.+n(n+1)(n+2)
1x2x3+2x3x4+.+nx(n+1)(n+2)=?
1x2x3+2x3x4+.+n(n+1)(n+2)=?
求和1x2x3+2x3x4+...+n(n+1)(n+2)
1x2x3+2x3x4+…+n(n+1)
1x2x3+2x3x4+3x4x5+…+8x9x10
1x2x3+2x3x4+3x4x5+.+10x11x12
1x2x3+2x3x4+3x4x5+...+7x8x9=,
1x2X3+2x3X4+3x4X5+…+7X8X9=?
1x2x3 2x3x4 3x4x5 .10x11x12,怎么算
求和：1X2X3+2X3X4+3X4X5+...+98X99X100