The equation of the line through the intersection of \(3 x-4 y+1\) and \(5 x+y-1=0\) which cuts off equal…

The equation of the line through the intersection of \(3 x-4 y+1\) and \(5 x+y-1=0\) which cuts off equal intercepts on the axes is given by
  1. \(23 x+23 y-11=0\)
  2. \(23 x+23 y+11=0\)
  3. \(23 x-23 y-11=0\)
  4. \(23 x-23 y+11=0\)

Solution

Equation of family of lines passes through the intersection of lines \(3 x-4 y+1=0\) and \(5 x+y-1=0\) is \(\begin{aligned} & (3 x-4 y+1)+\lambda(5 x+y-1) =0 \\ \Rightarrow & (3+5 \lambda) x+(\lambda-4) y+(1-\lambda) =0 \\ \Rightarrow & \frac{x}{\frac{\lambda-1}{5 \lambda+3}}+\frac{y}{\lambda-1} =1, \quad\{\lambda \neq 1\} \end{aligned}\) \(\because\) The obtain lines makes equal intercepts with the axes, so \(\begin{aligned} & \left|\frac{\lambda-1}{5 \lambda+3}\right| =\left|\frac{\lambda-1}{\lambda-4}\right| \\ \Rightarrow & |\lambda-4| =|5 \lambda+3| \quad \because \{\lambda \neq 1\} \\ \Rightarrow & \lambda =-\frac{7}{4}, \frac{1}{6} \end{aligned}\) \(\therefore\) Equation of required lines are \(-23 x-23 y+11=0\) and \(23 x-23 y+5=0\) or \(23 x+23 y-11=0\) and \(23 x-23 y+5=0\) Hence, option (a) is correct.

Asked in: AP EAMCET 2020 (21 Sep Shift 1)

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