The first question is the third choice. Divide by two to get proper squaring. Anytime there is a number in front of the x in a situation like that, always divide by that number on both sides first. Then go from there.
The second question is also the third choice. The square root of 64 is 8. It can't be negative because square rooting is always positive unless you want a weird "i" in there. That's for algebra 2 and beyond so don't worry about it mate.
