A flashlight mirror has the shape of a paraboloid of diameter 2 inches and depth inches, as shown in the figure. How far from the center of the mirror should the bulb be placed so that the emitted light rays are parallel to the axis of the
paraboloid

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.