Question

\(\dfrac{4}{5}+\left|x-\dfrac{2}{7}\right|=\left(-\dfrac{1}{2}\right)^2\)

Answer 1

`4/5+|x-2/7|=(-1/2)^2`

`4/5+|x-2/7|=1/4`

`|x-2/7|=1/4-4/5`

`|x-2/7|=-11/20` (Vô lí)

Vậy không có giá trị nào của `x` t/m

Answer 2

\(\dfrac{4}{5}+\left|x-\dfrac{2}{7}\right|=\left(-\dfrac{1}{2}\right)^2\)

\(\Rightarrow\dfrac{4}{5}+\left|x-\dfrac{2}{7}\right|=\dfrac{1}{4}\)

\(\Rightarrow\left|x-\dfrac{2}{7}\right|=\dfrac{5}{20}-\dfrac{16}{20}\)

\(\Rightarrow\left|x-\dfrac{2}{7}\right|=-\dfrac{11}{20}\)

mà \(\left|x-\dfrac{2}{7}\right|\ge0\)

\(\Rightarrow x\in\varnothing\)