Question

1)Tính già trị của biểu thức A:

A=1/2.3+1/3.4+........+1/49.50

Answer 1

\(A=\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{49.50}\)

\(A=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)

\(A=\frac{1}{2}-\frac{1}{50}\)

\(A=\frac{12}{25}\)

Answer 2

\(A=\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{49.50}\)

\(A=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)

\(A=\frac{1}{2}-\frac{1}{50}\)

\(A=\frac{12}{25}\)

Answer 3

\(A=\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{49\cdot50}\)

\(A=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)

\(A=\frac{1}{2}-\frac{1}{50}\)

\(A=\frac{25}{50}-\frac{1}{50}\)

\(A=\frac{24}{50}\)

Vậy \(A=\frac{12}{25}\)