It is an equation, telling you that left side of = is same as right side and asking you to solve it (figure out the x).
[tex]x^2=\frac{9}{256}[/tex]
Apply square root on both sides of the equation to get rid of power on x.
[tex]x=\pm\sqrt{\frac{9}{256}}[/tex]
Now simplity the square root.
[tex]x=\pm\frac{\sqrt{9}}{\sqrt{256}}=\boxed{\pm\frac{9}{16}}[/tex]
Hope this helps.
