Are these lines y = 2x + 3 and y = -1/2x - 1 perpendicular?

C. Only if they intersect at origin

SSC CGL 2025 PYQ — Question 56

SSC CGL - 22 Sep 2025 - Shift 2 • Quantitative Aptitude • Q56

Are these lines y = 2x + 3 and $y = -\frac{1}{2}x - 1$ perpendicular?

Show answer & explanation

Correct answer: A

Explanation

The correct answer is option 1 i.e. Yes.

y = 2x + 3

Slope = 2

$y = -\frac{1}{2}x - 1$

Slope = - 1/2

Product = 2 × (- 1/2) = –1 ⇒ Perpendicular