1/3+1/3*5+1/5*7+.+1/19*21
1个回答
1/3+1/3*5+1/5*7+.+1/19*21
=1/2*(1-1/3+1/3-1/5+1/5+.-1/21)
=1/2*(1-1/21)
=10/21
相关问题
1+3+5+7+···+21+23+21+19+17+···+7+5+3+1=?
1/3*1+1/3*5+1/5*7+A+1/17*19+1/19*21
请问,1/(1*3)+1/(3*5)+1/(5*7)+……+1/(17*19)+1/(19*21)怎么计算?
1*1/3+1/3*5+1/5*7+……+1/17*19+1/19*21要过程啊!
1/1*3+1/3*5+1/5*7+1/7*9+.1/19*21怎么算
1/1*3+1/3*5+1/5*7+...+1/19*21+1/21*23=( )的规律和答案
1/1X3+1/3X5+1/5X7...1/17X19+1/19X21=
计算1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+.+1/(19×21)
*3分之1+3*5分之1+5*7分之1+.19*21分之1=?
1/1×3+1/3×5+1/5×7+…1/17×19+1/19×21这道题如何简便运算?