The equation of the pair of lines through the point $(2,1)$ and perpendicular to the pair of lines $4 x y+2…

The equation of the pair of lines through the point $(2,1)$ and perpendicular to the pair of lines $4 x y+2 x+6 y+3=0$ is
  1. $x y-x-2 y+2=0$
  2. $x y+x-2 y-2=0$
  3. $x y+x+2 y-6=0$
  4. $x y-x+2 y-2=0$

Solution

Given pair of lines, $ \begin{aligned} & 4 x y+2 x+6 y+3=0 \\ \Rightarrow \quad & 2 x(2 y+1)+3(2 y+1)=0 \\ \Rightarrow \quad & (2 x+3)(2 y+1)=0 \end{aligned} $ So, equations of lines are $x=\frac{-3}{2}$ and $y=-\frac{1}{2}$ Equations of line passing through $(2,1)$ and perpendicular to the pair of lines $4 x y+2 x+6 y+3=0$ are $ y-1=0 \text { and } x-2=0 $ $\therefore \quad$ Combining the equation of lines are $ (y-1)(x-2)=0 \Rightarrow x y-x-2 y+2=0 $

Asked in: AP EAMCET 2017 (26 Apr Shift 1)

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