Question

`x−1/2−1/6−1/12−1/20=1/30`

Answer 1

\(x=\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}\)

\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}=\dfrac{5}{6}\)

Answer 2

x-1/2-1/6-1/12=1/30+1/20

x-1/2-1/6-1/12=1/12

x-1/2-1/6=1/12+1/12

x-1/2-1/6=1/6

x-1/2=1/6+1/6

x-1/2=1/3

x=1/3+1/2

x=2/6+3/6

x=5/6

Answer 3

`x - 1/2 - 1/6 - 1/12 - 1/20 = 1/30`

`=> x   = 1/30 + 1/20 + 1/12 + 1/6 + 1/2`

`=> x  = 5/6`

vậy `x = 5/6`