阅读理解
问题描述:
阅读理解
1/1*2=1/1-1/2 1/2*3=1/2-1/3 1/3*4=1/3-1/4...
∴计算1/1*2+1/2*3+1/3*4+...+1/2004*2005
=1/1-1/2+1/2-1/3+1/3-1/4+§+1/2004-1/2005
=1-1/2005
=2004/2005
理解以上方法的真正含义,计算:
1/1*3+1/3*5+§+1/2007*2009
答
1/1*3+1/3*5+§+1/2007*2009
=1/2×(1-1/3+1/3-1/5+……+1/2007-1/2009)
=1/2×(1-1/2009)
=1/2×2008/2009
=1004/2009