Đáp án + Giải thích các bước giải:
Ta có :
`x-\frac{20}{11.13}-\frac{20}{13.15}-\frac{20}{15.17}-....-\frac{20}{53.55}=\frac{3}{11}`
`→x-(\frac{20}{11.13}+\frac{20}{13.15}+\frac{20}{15.17}+....+\frac{20}{53.55})=\frac{3}{11}`
`→x-10(\frac{2}{11.13}+\frac{2}{13.15}+\frac{2}{15.17}+....+\frac{2}{53.55})=\frac{3}{11}`
`→x-10(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+....+\frac{1}{53}-\frac{1}{55})=\frac{3}{11}`
`→x-10(\frac{1}{11}-\frac{1}{55})=\frac{3}{11}`
`→x-10.\frac{4}{55}=\frac{3}{11}`
`->x-\frac{8}{11}=\frac{3}{11}`
`->x=\frac{3}{11}+\frac{8}{11}`
`->x=1(TM)`
Vậy `x=1`
