Tìm x, biết: a) (x + 1/5)^2 - 9/25 = 0 b) (x + 1/5)^2 + 17/25 = 26/25

* Hướng dẫn giải

a) ${\left(x+\frac{1}{5}\right)}^2-\frac{9}{25}=0\Rightarrow {\left(x+\frac{1}{5}\right)}^2=\frac{9}{25}$$\Rightarrow \left[\begin{array}{l}x+\frac{1}{5}=\frac{3}{5}\\ x+\frac{1}{5}=\frac{-3}{5}\end{array}\right.\Rightarrow \left[\begin{array}{l}x=\frac{2}{5}\\ x=\frac{-4}{5}\end{array}\right.$

b) ${\left(x+\frac{1}{5}\right)}^2+\frac{17}{25}=\frac{26}{25}\Rightarrow {\left(x+\frac{1}{5}\right)}^2=\frac{9}{25}$$\Rightarrow \left[\begin{array}{l}x=\frac{2}{5}\\ x=\frac{-4}{5}\end{array}\right.$