[(2/3-1/4)÷5/6+4/5]X5/11
1x5+2x5+3x5+4x5+5x5… 麻烦给我一个公式.
[(2/3-1/4)÷5/6+4/5]X5/11
[1又2分之3减(1/3-1/6+5/12)x2.4]x5
求前n项和1.1/(2X5),1/(5X8),1/(8X11)...2.2^2/(1X3),4^2/(3X5),6^2/
11/4/(2/3-(1/2+3/5)x5/9)怎么算
sn=(2-3x5^-1)+(4-3x5^-2)+…+(2n-3x5^-n)要详解答案,急用!
1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101
(1+2+3+4+5+6+7+8+9+10+11+12+13+14+15)x5=?
已知数据X1,X2,X3,X4,X5的平均数是X拔,则一组新数据X1+1,X2+2,X3+3,X4+4,X5+5的平均数
6分之5+3分之5×5分之4 /(2分之1-6分之1)x5分之3÷5分之1简便运算
说出下面各算式的意义15x4 5x0.12 0.12x5 2/7x2/5 2/7x5 1÷0.125 4/1÷2/3 5
1x1 2x2 3x3 4x4 5x5```````nxn有什么规律