Question

Directrix of the parabola 5x² – 30x + 2y = 0 is

• A. 10y + 69 = 0
• B. 10y – 69 = 0
• C. 10x – 69 = 0
• D. None of these

Answer 1

Answer: (D)

None of these

Answer 2

5x² – 30x = – 2y

x² – 6x + 9 = –$\frac{2}{5}$y + $\frac{9 \times 2 \times 5}{2 \times 5}$

(x – 3)² = –$\frac{2}{5}\left( y - \frac{45}{2} \right)$ ̃ X² = –$\frac{2}{5}$Y

Y = 1/10

y – $\frac{45}{2}$ = 1/10 ̃ y = $\frac{45}{2}$+ $\frac{1}{10}$