Question

If lines represented by equation px² - qy² = 0 are distinct, then ______ 

Options

• pq > 0

• pq < 0

• pq = 0

• p + q = 0

Answer 1

If lines represented by equation px² - qy² = 0 are distinct, then pq > 0.

Explanation:

Given equation of pair of lines is

px² - qy² = 0

∴ a = p, b = -q, h = 0

Since the lines are real and distinct,

h² - ab > 0

⇒ 0 - p(-q) > 0

⇒ pq > 0