Chứng minh rằng 1/1.2 + 1/2.3 + 1/3.4 +........+1/49+50 = 1/26 + 1/27 +1/28 +.....+ 1/50
|x+1/1.2|+|x+1/2.3|+|x+1/3.4|+...+|x+1/99.100|=100x
\(1+\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}\)
tính \(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{99.100}\)
Bài 1. Tính A = 1.2 + 2.3 + 3.4 + … + n.(n + 1)
Cho A= 1/1.2 +1/2.3 +1/3.4 +......+1/49+50. Chứng minh rằng 7/ 12 < A < 5/6
Cho :A=1/1.2 +1/2.3 + 1/3.4 + .......+1/49+50. Chứng minh rằng 7/12 < A < 5/6.
CMR: \(\frac{1.2-1}{2!}+\frac{2.3-1}{3!}+\frac{3.4-1}{4!}+...+\frac{99.100-1}{100!}< 2\)
Tính B = \(\dfrac{1-1.2}{2!}+\dfrac{1-2.3}{3!}+...+\dfrac{1-99.100}{100!}\)