Line R goes through points (5,2) and (1,4) on an XY plane. Line S is perpendicular to Line R. What is the slope of Line S?

What do you mean by that?

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.