\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)
\(=\frac{1}{2}-\frac{1}{50}\)
\(=\frac{25}{50}-\frac{1}{50}=\frac{24}{50}\)
cho A = 1/1.2+1/2.3+1/3.4+...+1/49.50 ; cho B = 1.2+1.3+3.4+....+49.50
tính 50mủ 2A - B/17
Tính nhanh A = 1/1.2 + 1/2.3 + 1/3.4 + 1/3.4 + ... + 1/49.50
1/1.2+1/2.3+1/3.4+.....+1/49.50
A= 1/1.2 + 1/2.3+1/3.4+...+ 1/49.50
(1/1.2+1/2.3+1/3.4+…+1/49.50)x=49/50
a, 1/2+1/2.3+1/3.4+1/4.5+.....+1/49.50
chứng tỏ rằng: 1/1.2+1/2.3+1/3.4+...+1/49.50<1
3. tính:
A=\(\dfrac{1}{1.2}\)+\(\dfrac{1}{2.3}\)+\(\dfrac{1}{3.4}\)+...+\(\dfrac{1}{49.50}\)
chứng minh rằng 1/1.2 + 1/2.3 + 1/3.4+ 1/4.5+ ...+1/49.50 <1
