Question

Equation of line passing through the point $(1,2)$ and perpendicular to the line $y = 3x -1$ is

• A. $x + 3y - 7 = 0$
• B. $x + 3y + 7 = 0$
• C. $x + 3y = 0$
• D. $x - 3y = 0$

Answer 1

Answer: (A)

Given line is
$y=3 x-1$
$\therefore $ Slope of the given line $=3$
$\therefore $ Slope of a line perpendicular to the given line $=-\frac{1}{3}$
$\therefore $ Equation of required line will be
$ y-2 =\frac{-1}{3}(x-1) $
$\Rightarrow 3 y-6 =-x+1 $
$\Rightarrow x+3 y -7 =0$