1/4x 7/4y等于2。

1/1*4=1/3*(1/1-1/4)1/4*7=1/3*(1/4-1/7)依次可得：原式=1/3*(1-1/4+1/4-1/7+1/7-1/10……+1/2007-1/2010)=1/3*(1-1/

原式=4/3+16/15+36/35+...+400/399=1/3+1/15+1/35+...+1/399+10=1/3+【（1/3-1/5）+（1/5-1/7）+（1/7-1/9）+...+（1/

＝3(1/1-1/4)+3(1/4-1/7)＋……＋3(1/2002-1/2005)＋3(1/2005-1/2008)＝3(1/1-1/4+1/4-1/7+……＋1/2002=1/2005+1/200

1/1x4+1/4x7+1/7x10+1/10x13+1/13X16=(1/3)×[(1-1/4)+(1/4-1/7)+(1/7-1/10)+(1/10-1/13)+(1/13-1/16)]=(1/3

1/(1x4)+1/(4x7)+1/(7x10)+...+1/(3n-2)x(3n+1)]=1/3*(1-1/4+1/4-1/7+.+1/(3n-2)-1/(3n+1))=1/3*(1-1/(3n+1

1/1*4=1/3*(1/1-1/4)1/4*7=1/3*(1/4-1/7)依次可得：原式=1/3*(1-1/4+1/4-1/7+1/7-1/10……+1/2002-1/2005+1/2005+1/2

1/1X4+1/4X7+1/7X10+...+1/100X103=1/3×(1-1/4)+1/3×(1/4-1/7)+1/3×(1/7-1/10)+...+1/3×(1/100-1/103)=1/3×

100x(3/1x4+3/4x7+3/7x10+.3/97x100)=100x[(1-1/4)+(1/4-1/7)+(1/7-1/10)+……+(1/97-1/100)]=100x[(1+1/4+1/

2/7X7=2;4分之1X7分之5+4分之1X7分之2+4分之1=(1/4)×(5/7+2/7+1)=(1/4)×2=1/2;98除以（15分之1除以7分之2）=98÷(1/15×7/2)=98×30

很遗憾,我只想到这个.1+2x3+[(4x5+6)x7+8]x9=17171+2*3+[(4*5+6)*7+8]*9=17171+2x3+{（4x5+6）x7+8}x9=1717

1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7=6/7因为1/1*2=1-1/2同理

是奇数,因为出第一项的1以外,都是一个偶数和一个奇数的乘积再问：还列算式吗？

原式=1/3（1-1/4+1/4-1/7+……+1/3n-2-1/3n+1）=1/3(1-1/3n+1)=1/3(3n/3n+1)=n/3n+1

1x4分之一加4x7分之一加到（3n-2）x（3n+1）分之一=1/1x4+1/4x7+.+1/(3n-2)(3n+1)=1/3[1-1/4+1/4-1/7+...+1/(3n-2)-1/(3n+1)

7^4-3x7^2-8x7^3=7^2x(7^2-3-8x7)=7^2x(49-3-56)=49x(-10)=-490(x+y)^2-2(x^2-y^2)+(x-y)^2=(x+y)^2-2(x+y)

x2+y2＝(x+y)2-2xy＝14x3+y3＝(x2+y2)×(x+y)-xy2-yx2＝14×4-xy(x+y)=52……剩下的就是这么个算法,手机党,求个最佳哈

% matlab 程序X=[7 4 8.5 9.5 3 1 8 5];Y=[11 8.5 

3/8=15/40(3/5)/(3/7)=(4/5)/(4/7)

1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7=（1-1/2）+（1/2-1/3）+（1/3-1/4）+（1/4-1/5）+（1/5-1/6）+（1/6-1/7）=1-1/7=

4分之1x+4x7=241/4x=24-281/4x=-4x=-16如果本题有什么不明白可以追问,