Question

The equation of the line perpendicular to line $a x + b y + c = 0$ and passing through $( a , b )$is equal to.

• A. $b x - a y = 0$
• B. $b x + a y - 2 a b = 0$
• C. $b x + a y = 0$
• D. None of these

Answer 1

Answer: (A)

$b x - a y = 0$

Answer 2

Equation of line perpendicular to $a x + b y + c = 0$ is $b x - a y + \lambda = 0$ .....(i)

It passes through (a, b)

So, from equation (i), $a b - a b + \lambda = 0 \Rightarrow \lambda = 0$

So equation of line is $b x - a y = 0$.