What is the equation of the quadratic graph with a focus of (3, 1) and a directrix of y = 5? f(x) = one eighth (x − 3)2 + 3 f(x) = −one eighth (x − 3)2 + 3 f(x) = one eighth (x − 3)2 − 3 f(x) = −one eighth (x − 3)2 − 3