> 数学 >
已知:根号a-1+(ab-2)²=0
求:1/(a+1)(b+1)+1/(a+2)(b+2)+……+1/(a+2007)(b+2007)+1/(a+2008)(b+2008).
人气:193 ℃ 时间:2019-12-13 07:44:18
解答
根号a-1+(ab-2)²=0
所以有a-1=0且ab-2=0
得到a=1,b=2
那么,1/(a+1)(b+1)+1/(a+2)(b+2)+……+1/(a+2007)(b+2007)+1/(a+2008)(b+2008)=1/2*3+1/3*4+.+1/2009*2010
=1/2-1/3+1/3-1/4+.+1/2009-1/2010
=1/2-1/2010
=502/1005我出错题了,应该是求:1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+……+1/(a+2007)(b+2007)+1/(a+2008)1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+……+1/(a+2007)(b+2007)+1/(a+2008)(b+2008)=1/1*2+1/2*3+1/3*4+...+1/2009*2010=1-1/2+1/2-1/3+1/3-1/4+...+1/2009-1/2010=1-1/2010=2009/2010
推荐
猜你喜欢
© 2024 79432.Com All Rights Reserved.
电脑版|手机版