Question

The equation 12x² + 7xy + ay² + 13x - y + 3 = 0 represents a pair of perpendicular lines. Then the value of 'a' is ______  

Options

• `7/2`

• -19

• -12

• 12

Answer 1

The equation 12x² + 7xy + ay² + 13x - y + 3 = 0 represents a pair of perpendicular lines. Then the value of 'a' is -12.

Explanation:

Comparing the given equation with

Ax² + 2Hxy + By² + 2Gx + 2Fy + C = 0, we get

A = 12 and B = a.

For perpendicular lines, A + B = 0.

∴ 12 + a = 0 ⇒ a = -12