A parabola has its vertex at (0,0)(0, 0)(0,0) and passes through (2,4)(2, 4)(2,4). What is its equation?
y=x2y = x^2y=x2
y=2x2y = 2x^2y=2x2
y=x2+2y = x^2 + 2y=x2+2
x=18y2x = \frac{1}{8}y^2x=81y2