rememember, you can do anything to an equation as long as you do it to both sides
also, remember that [tex]\sqrt{\frac{a}{b}}=\frac{\sqrt{a}}{\sqrt{b}}[/tex]
so
assuming you mean [tex]x^2=\frac{16}{49}[/tex]
square root both sides
[tex]x=\sqrt{\frac{16}{49}}[/tex]
[tex]x=\frac{\sqrt{16}}{\sqrt{49}}[/tex]
[tex]x=\frac{4}{7}[/tex]
