1/1×3 + 1/3×5 + 1/5×7 +.+ 1/19×21=
1/1×3 + 1/3×5 + 1/5×7 +.+ 1/19×21=
1/3*1+1/3*5+1/5*7+A+1/17*19+1/19*21
1/3*1+1/3*5+1/5*7+----1/17*19+1/19*21=
计算1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+.+1/(19×21)
-1/1*3-1/3*5-1/5*7-1/7*9-^-1/19*21
1/1*3+1/3*5+1/5*7+~1/19*21=简算原理
(1/1+3)+(1/3+5)+(1/5+7)+.(1/19+21)=?(简便计算)
1/1*3+1/3*5+1/5*7+1/7*9.1/17*19+1/19*21结果是多少?
1/1*3+1/3*5+1/5*7+1/7*9.1/17*19+1/19*21怎么做?
(1+3)/1+(3+5)/1+(5+7)/1+(7+9)/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怎么做?
1×3 +3×5 +5×7 .+19×21 等于多少