3*5/1+5*7/1+7*9/1+9*11/1+.+37*39/1=( )
3*5/1+5*7/1+7*9/1+9*11/1+.+37*39/1=( )
1-3+5-7+9-11+13-.-39+41=?
1/(1*3*5)+1/(3*5*7)+1/(5*7*9)+1/(7*9*11)+1/(9*11*13+)1/(11*1
计算:1-3+5-7+9-11+13-...-39+41.
简算:1/1*3+1/3*5+1/5*7+1/7*9+1/9*11
(1/3+1/5+1/7+1/9)*(1/5+1/7+1/9+1/11)-(1/3+1/11+1/5+1/7+1/9)*
计算:1/3*5+1/5*7+1/7*9+1/9*11+1/11*13
找规律:1+3+5+7+9=?;1+3+5+7+9+11=?;1+3+5+7+9+11+13=?..1+3+5+7+9.
1+3+5+9+...+37+39
1/3+1/5+1/7+1/9+1/11+1/13+1/15=
1+3+5+7+9+11+--------+2n-1=?
1+3+5+7+...+37+39