CHO TOG TRÊN LÀ A
\(A=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{110.111}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{110}-\frac{1}{111}\)
\(=1-\frac{1}{111}\)
\(=\frac{110}{111}\)
1/1.2 + 1/2.3 + 1/3.4 + ... + 1/2003.2004 = ?
1/1.2+1/2.3+1/3.4+...1/100.101
1/1.2+1/2.3+1/3.4+1/4.5+1/5.6 = ?
1/1.2 + 1/2.3 + 1/3.4 +...............+1/n(n+1)
A=1/1.2+1/2.3+1/3.4+1/4.5+....+1/2018.2019
[1/1.2+1/2.3+1/3.4+..............+1/19.20];x=9/10
So sánh 1/1.2 + 1/2.3 + 1/3.4 +....+ 1/49.50 với 1
1/1.2+1/2.3+1/3.4...+1/9.10
tính nhanh:
A = \(\dfrac{1}{1.2}\)+\(\dfrac{1}{2.3}\)+\(\dfrac{1}{3.4}\)+........+\(\dfrac{1}{149.150}\)
