Question

Find the equation of the parabola which is symmetrical about x-axis and passing through (–2, –3).

Answer 1

Equation of the parabola symmetrical about X-axis is either y² = 4ax or y² = - 4ax.

Since the parabola passes through (-2, -3) it will be of the form y² = - 4ax   ...(1)

Substituting (-2, -3) in (1) we get, 

y² = - 4ax

(-3)² = - 4a(-2)

⇒ 9 = 8a

⇒ a = `9/8`

Substituting a = `9/8` in (1) we get,

y² = - 4ax

y² = - 4`(9/8)`x

⇒ y² = `(-9)/2`x

which is required equation of the parabola.