Question

A = \(\dfrac{1}{2}\)+\(\dfrac{5}{6}\)+\(\dfrac{11}{12}\)+\(\dfrac{19}{20}\).
Cho em hỏi với ạ

Answer 1

\(A=1-\dfrac{1}{2}+1-\dfrac{1}{6}+1-\dfrac{1}{12}+1-\dfrac{1}{20}\)

\(=4-\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}\right)\)

\(=4-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}\right)\)

=4-4/5=16/5

Answer 2

Answer 3

`A=1/2+5/6+11/12+19/20`

`A=(1/2+19/20)+(5/6+11/12)`

`A=(10/20+19/20)+(10/12+11/12)`

`A=29/20+21/12`

`A=87/60+105/60=192/60=16/5`

Answer 4

\(A=\dfrac{5}{6}+\dfrac{19}{20}=\dfrac{50}{60}+\dfrac{57}{60}=\dfrac{107}{60}\)