Question

The order of differential equations of all parabolas having directrix parallel to x-axis is

• A. 3
• B. 1
• C. 4
• D. 2

Answer 1

Answer: (A)

3

Answer 2

The equation of all parabolas having directrices parallel to x-axis is $( x - h ) ^ { 2 } = \pm 4 a ( y - k )$.

There are three arbitrary constants, h, k and a.

$\therefore$ order = 3.