Question:medium

The equation to the line through the point of intersection of \(x - y + 1 = 0\), \(3x + 2y + 4 = 0\) and perpendicular to \(x - 4y = 0\) is

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Always solve intersection carefully—small arithmetic errors change the final answer.
Updated On: Apr 18, 2026
  • \(4x + y + 5 = 0\)
  • \(4x + y + 3 = 0\)
  • \(4x + y - 5 = 0\)
  • \(4x + y - 3 = 0\)
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The Correct Option is A

Solution and Explanation

Step 1: Understanding the Concept:
We first need to find the specific point where the two lines intersect. Then, we find the slope of the line perpendicular to the given reference line and use the point-slope form to find the final equation.
Step 2: Detailed Explanation:
1. Find point of intersection:
Solve the system: \[ x - y + 1 = 0 \quad \dots(i) \] \[ 3x + 2y + 4 = 0 \quad \dots(ii) \] From \((i)\), \( y = x + 1 \). Substitute this into \((ii)\): \[ 3x + 2(x + 1) + 4 = 0 \] \[ 3x + 2x + 2 + 4 = 0 \implies 5x = -6 \implies x = -6/5 \] Find \( y \): \[ y = -6/5 + 1 = -1/5 \] Intersection point is \( (-6/5, -1/5) \).
2. Find the slope:
The given line is \( x - 4y = 0 \). Its slope (\( m_{1} \)) is \( 1/4 \).
The required line is perpendicular to it, so its slope (\( m \)) must satisfy \( m \cdot m_{1} = -1 \). \[ m = -4 \] 3. Equation of the line:
Using point-slope form \( y - y_{1} = m(x - x_{1}) \): \[ y - (-1/5) = -4(x - (-6/5)) \] \[ y + 1/5 = -4x - 24/5 \] Multiply the entire equation by 5: \[ 5y + 1 = -20x - 24 \] \[ 20x + 5y + 25 = 0 \] Divide by 5: \[ 4x + y + 5 = 0 \].
Step 3: Final Answer:
The equation of the line is \( 4x + y + 5 = 0 \).
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