Question

A=\(\frac{5}{2.4}+\frac{5}{4.6}+...\frac{5}{48.50}\)

Answer 1

\(A=\frac{5}{2.4}+\frac{5}{4.6}+...+\frac{5}{48.50}\)

\(A=\frac{5}{2}\left(\frac{1}{2.4}+\frac{1}{4.6}+...+\frac{1}{48.50}\right)\)

\(A=\frac{5}{2}\left(\frac{1}{2}-\frac{1}{50}\right)\)

\(A=\frac{6}{5}\)

Answer 2

=\(\frac{1}{5}.\left(\frac{1}{2}.\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+...+\frac{1}{48}-\frac{1}{50}\right)\right)\)

=\(\frac{1}{5}.\left(\frac{1}{2}.\left(\frac{1}{2}-\frac{1}{50}\right)\right)\)

=\(\frac{1}{5}.\left(\frac{1}{2}.\frac{12}{25}\right)\)

=\(\frac{1}{5}.\frac{6}{25}=\frac{6}{125}\)

Vậy \(A=\frac{6}{125}\)

Answer 3

A = (5/2 - 5/4) + (5/4-5/6) +....+(5/48-5/50)

A = 5/2 + ( 5/4-5/4) +(5/6-5/6)+....+(5/48-5/48)+5/50

A = 5/2-5/50

A = 125/50-5/50

A = 120/50 = 12/5

Answer 4

2A = 2( 5/2.4 + 5/4.6 +...+ 5/48.50 )

2A = 5( 2/2.4 + 2/4.6 +...+ 2/48.50 )

2A = 5( 1/2-1/4 + 1/4-1/6 +...+ 1/48-1/50 )

2A = 5( 1/2-1/50 )

2A = 5.24/50 → A= 5.24/25 = 24/5