1/1×3+1/3×5+1/5×7+…+1/17×19+1/9×21=?
1/1×3+1/3×5+1/5×7+…+1/17×19+1/9×21=?
1*3/1 + 3*5/1 + 5*7/1+ ……+ 17*19 /1 +19*21/1=
(1+3)/1+(3+5)/1+(5+7)/1+(7+9)/1.+(17+19/1+(19+21)/1=?
1/3*1+1/3*5+1/5*7+----1/17*19+1/19*21=
巧算:1/1×3+ 1/3×5+ 1/5×7 + …… +1/17×19
1/1*3+1/3*5+1/5*7+1/7*9+...1/17*19=
1*3/1+3*5/1+5*7/1+……+17*19/1+19*21/1
1/1*3+1/3*5+1/5*7+……+1/17*19+1/19*21
1×3x5+3×5×7+5×7×9+……+17×19×21
1/1×3+1/3×5+1/5×7+…1/17×19+1/19×21这道题如何简便运算?
1/1*3 + 1/3*5 + 1/5*7 + …+ 1/17*19 + 1/19*21 如何计算
1/3*1+1/3*5+1/5*7+A+1/17*19+1/19*21