1x4+4x7+7x11+……+n(n+3)=?分解因式啊~~~
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1x4+4x7+7x11+……+n(n+3)=?分解因式啊~~~1x4+4x7+7x11+……+n(n+3)=?分解因式啊~~~1x4+4x7+7x11+……+n(n+3)=?分解因式啊~~~原式=∑
1x4+4x7+7x11+……+n(n+3)=?分解因式啊~~~
1x4+4x7+7x11+……+n(n+3)=?
分解因式啊~~~
1x4+4x7+7x11+……+n(n+3)=?分解因式啊~~~
原式=∑（n²+3n）=∑n²+3∑n
=n（n+1）(2n+1)/6+3n(n+1)/2
=n(n+1)[2n+1+9]/6
=n(n+1)²（n+5）/2
1x4+4x7+7x11+……+n(n+3)=?分解因式啊~~~
1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9+9x10+10x11+ +nx(n+1)=
1/1x4+1/4x7+1/7x11+*******1/97x100=?*是省略号
1X4分之一+4X7分之一+7X11分之一.+97X101分之一等于多少
1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9+9x10+10x11
lim[1/(1x4)+1/(4x7)+1/(7x10)+...+1/(3n-2)x(3n+1)]=_____
1/5x7+1/7x9+1/9x11+1/11x13+…+1/23x25
1/1x4+1/4x7+…+1/97x100
1/2x4+1/3x5+1/4x6+1/5x7+.1/8x10+1/9x11
1/1x4+1/4x7+1/7x10+……+1/2005x2008佼佼我
1/1x4+1/4x7+1/7x10+……+1/97x100SOS!SOS!
1/1x4+1/4x7+1/7x10+……+1/2005x2008
计算：1/（1x4）+1/（4x7）+1/(7x10)…+1/(298x301)
1X4/1+4X7/1+7X10/1+…+2005X2008/1=?
1/1x4 + 1/4x7 + 1/7x10 +…+ 1/91x94=?
1X4/1+4X7/1+7X10/1+…+2005X2008/1=?
1x2+2x3+3x4...+10x11=?1x2+2x3+3x4...+nx(n-1)=?
数学建模的LINGO使用问题modelmin=x0+x11+x8+x9;x0+x1+x2+x3+x4+x5+x6+x7+x8+x9+x10+x11=11;x0+x1+x3+x4>=4;x1+x2+x4+x5>=4;x2+x3+x5+x6>=4;x3+x4+x6+x7>=3;x4+x5+x7+x8>=3;x5+x6+x8+x9>=4;x6+x7+x9+x10>=4;x7+x8+x10+x11>=2;x8+x9+x11+x0>=2;x9+x10+x0+x1>=1;