问道数学算术题!必须用简便计算!过程结果都要有!
问题描述:
问道数学算术题!必须用简便计算!过程结果都要有!
1/(1x4)+1/(4x7)+1/(7x10)+1/(10x13)+1/(13x16)
答
1/(1x4)+1/(4x7)+1/(7x10)+1/(10x13)+1/(13x16)
=1/4+1/3*(1/4-1/7)+1/3*(1/7-1/10)+1/3*(1/10-1/13)+1/3*(1/13-1/16)
=1/4+1/12-1/3*1/16
=5/16