计算1*3分之一+3*5分之一+5*7分之一+...+2007*2009分之一

2024-12-28 09:16:34
推荐回答(2个)
回答1:

解:原式=(1-1/3)/2+(1/3-1/5)/2+…+…+(1/2007-1/2009)/2=(1-1/2009)/2=1004/2009

回答2:

1/﹙1×3﹚+1/﹙3×5﹚+1/﹙5×7﹚+ …… +1/﹙2007×2009﹚
=1/2×[(3-1) /﹙1×3﹚+(5-3)/﹙3×5﹚+(7-5)/﹙5×7﹚+ …… +(2009-2007)/﹙2007×2009﹚]
=1/2×(1-1/3+1/3-1/5+1/5-1/7+ …… +1/2007-1/2009﹚
=1/2×(1-1/2009﹚
=1004/2009