My book says this: "[math]\displaystyle(3^2 - 8)^{\frac{1}{2}} = 3 - 4 \rightarrow 1 = -1 \rightarrow [/math]false", but [math]1^{\frac{1}{2}}[/math] can also be equal to [math]-1[/math], because [math]-1[/math] squared is [math]1[/math], isn't it?