3⼀10*11+3⼀11*12+3⼀12*13++++3⼀19*20等于几详解

2024-12-30 12:32:02
推荐回答(1个)
回答1:

3(1/10*11+1/11*12+1/12*13++++1/19*20)
=3(1/10-1/11+1/11-1/12+.....+1/19-1/20)
=3*(1/10-1/20)
=3/10