Find an equation whose graph is a parabola with directrix y= -1 and vertex (1,3)?

Question

 Find an equation whose graph is a parabola with directrix y= -1 and vertex (1,3). 

Answer 1

y = a(x - 1)² + 3

directrix: y = k - p

-1 = 3 - p

p = 4

a = 1/4p

a = 1/16

 

y = (1/16)(x -1)² + 3