The equation of a parabola with vertex at the origin and symmetric about the y-axis is x2 = 4ay
Since point P(2,-3) passes through above parabola we can write,
22 = 4a(-3)
4 = -12a
a = \(-\frac{1}{3}\)
Therefore, the equation of a parabola is
x2 = 4.\(\Big(-\frac{1}{3}\Big)y\)
x2 = \(-\frac{4}{3}y\)
3x2 = -4y