Question

Tính

\(\frac{2^2}{1.3}.\frac{3^2}{2.4}.\frac{4^2}{3.5}.......\frac{50^2}{49.51}\)

Answer 1

52/51

Answer 2

 

\(\text{= 2/1 . 2/3 . 3/2 . 3/4 . 4/3 . 4/5 ....... 50/49.50/51 }\)

Dùng phương pháp khử liên tiếp ta có

\(=\frac{2}{1}-\frac{50}{51}=\frac{52}{51}\)

Answer 3

í nhầm

Answer 4

\(=\frac{2}{1}.\frac{2}{3}.\frac{3}{2}\frac{3}{4}.\frac{4}{3}.\frac{4}{5}......\frac{50}{49}.\frac{50}{51}=\frac{2}{1}.\frac{1}{51}=\frac{2}{51}\)