Question

tìm x biết (x+1)^2=4/25

Answer 1

(\(x\) + 1)² = \(\dfrac{4}{25}\)

(\(x+1\))² = (\(\dfrac{2}{5}\))²

\(\left[{}\begin{matrix}x+1=-\dfrac{2}{5}\\x+1=\dfrac{2}{5}\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=\dfrac{2}{5}-1\\x=-\dfrac{2}{5}-1\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=-\dfrac{3}{5}\\x=-\dfrac{7}{5}\end{matrix}\right.\)

Vậy \(x\in\){  \(-\dfrac{7}{5}\) ; - \(\dfrac{3}{5}\)} 

Answer 2

`@` `\text {Ans}`

`\downarrow`

`(x+1)^2 = 4/25`

`=> (x+1)^2 = (+-2/5)^2`

`=>`\(\left[{}\begin{matrix}x+1=\dfrac{2}{5}\\x+1=-\dfrac{2}{5}\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=\dfrac{2}{5}-1\\x=-\dfrac{2}{5}-1\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=-\dfrac{3}{5}\\x=-\dfrac{7}{5}\end{matrix}\right.\)

Vậy, `x \in {-3/5; -7/5}.`