(1)1,-1/3,1/5,-1/7,1/9,-1/11,1/13……第199个数是( )(2)2,-1,3,-1,4,-1,5,-1,6……第199个数是( )写一下你的解题思路哈……写出算式
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简便运算 (1+1/3+1/5+1/7)*(1/3+1/5+1/7+1/9)-(1+1/3+1/5+1/7+1/7+1/9)*(1/3+1/5+1/7)
算术题,(1+1/3+1/5+1/7)×(1/3+1/5+1/7+1/9)-(1+1/3+1/5+1/7+1/9)×(1/3+1/5+1/7)
数奥题(1+1/3+1/5+1/7)*(1/3+1/5+1/7+1/9)-(1+1/3+1/5+1/7+1/9)*(1/3+1/5+1/7)求(1+1/3+1/5+1/7)*(1/3+1/5+1/7+1/9)-(1+1/3+1/5+1/7+1/9)*(1/3+1/5+1/7)的简便算法要求:
(1)1+1/2+1/3+1/4+1/5+1/6+1/7+1/14+1/28
1/1*3=1/2(1-1/3)1/3*5=1/2(1/3-1/5)1/5*7=1/2(1/5-1/7).1/17*19=1/2(1/17-1/19)所以1/1*3+1/3*5+1/5*7+.1/17*19=1/2(1-1/3)+1/2(1/3+1/5)+1/2(1/5-1/7)+.1/2(1/17-1/19)=1/2(1-1/3+1/3-1/5+1/5-1/7+1/7.+1/17-1/19)=1/2(1-1/1
(1+1/3+1/5+1/7)*(1/3+1/5+1/7+1/9)-(1+1/3+1/5+1/7+1/9)*(1/3+1/5+1/7) 简算(1+1/3+1/5+1/7)*(1/3+1/5+1/7+1/9)-(1+1/3+1/5+1/7+1/9)*(1/3+1/5+1/7) 简便计算
因为1/1*3=1/2*(1-1/3),1/3*5=1/2*(1/3-1/5),1/5*7=1/2*(1/5-1/7),.,1/17*19=1/2*(1/17-1/19)所以1/1*3+1/3*5+1/5*7+...+1/17*19=1/2*(1-1/3)+1/2*(1/3-1/5)+1/2*(1/5-1/7)+...+1/2*(1/17-1/19)=1/2*(1-1/3+1/3-1/5+1/5-1/7+...+1/17-1/19)=1/2*(1-1/19)=9/19(1
(-1-1/2)*(-1-1/3)*(-1-1/4)*(-1-1/5)*(-1-1/6)*……*(-1-1/9)*(-1-1/10)(-1-1/2)*(-1-1/3)*(-1-1/4)*(-1-1/5)*(-1-1/6)*(-1-1/7)*(-1-1/8)*(-1-1/9)*(-1-1/10)
1/3+1/5+1/7+.+1/2n+1
((1/2)-1)*((1/3)-1)*((1/4)-1)*((1/5)-1)*((1/6)-1)*((1/7)-1)*((1/8)-1)*((1/9)-1)*((1/10)-1)
(1-1/2)乘以(1-1/3)乘以(1-1/4)乘以(1-1/5)乘以(1-1/6)乘以(1-1/7)的计算过程
简便计算:1、1/3+1/6+1/10+1/15+1/21+1/28+.+1/1202、1/4+1/12+1/24+1/40+.+1/198003、1+1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+.+1/(1+2+3+4+.+50)4、(3*3-1)/(3*3+1)+(5*5-1)/(5*5+1)+(7*7-1)/(7*7+1)+.+(1995*1995-1
(1/3+1/5+1/7)*(1/5+1/7+1/9)-(1/3+1/5+1/7+1/9)*(1/5+1/7)=?
1 1 1 1 1 3 5 7 1 5 13 25 1 7 25 why
1,3/-1,5/1,7/-1,9/1,11/-1,13/1,15/-1,(第2012个数)
1/1×3+1/3×5+1/5×7+···+1/(2n-1)(2n+1)
(1+2分之1)*(1+4分之1)*(1+6分之1)*(1+8分之1)*(1+10分之1)*(1-3分之1)*(1-5分之1)*(1-7分之)*(1-9分之1)
(1+1/2)*(1+1/4)*(1+1/6)*...*(1+1/2008)*(1-1/3)*(1-1/5)*(1-1/7)*...*(1-1/2007)