1/1×4+1/4×7+1/7×10+1/10×13+···+1/2008×2011 =

来源:学生作业帮助网 编辑:作业帮 时间:2024/07/11 15:57:34
1/1×4+1/4×7+1/7×10+1/10×13+···+1/2008×2011 =
x10 E(jl7aHs8(btl9ȽMq-ޘDD|z$6iηNP(khsom`l c'lɃsNdkދ1)k

1/1×4+1/4×7+1/7×10+1/10×13+···+1/2008×2011 =
1/1×4+1/4×7+1/7×10+1/10×13+···+1/2008×2011 =

1/1×4+1/4×7+1/7×10+1/10×13+···+1/2008×2011 =
1/(1×4)+1/(4×7)+1/(7×10)+1/(10×13)+···+1/(2008×2011)
=(1-1/4)/3+(1/4-1/7)/3+...+(1/2008-1/2011)/3
=(1-1/4+1/4-1/7+...+1/2008-1/2011)/3
=(1-1/2011)/3
=670/2011