Question:

The equation of the line passing through $ (0,0) $ and intersection of $ 3x-4y=2 $ and $ x+2y=-4 $ is

Updated On: Apr 29, 2024
  • $ 7x=6y $
  • $ 6x=7y $
  • $ 5x=8y $
  • $ x=0 $
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The Correct Option is A

Solution and Explanation

The correct answer is A:\(7x=6y\)
Given lines, \(3x-4y=2\) ..(i) 
\(x+2y=-4\) ..(ii)
Intersection point of these line is 
\(3(-4-2y)-4y=2\) \(-12-6y-4y=2\)
\(10y=-14\,\,\,\,\Rightarrow \,\,\,y=-7/5\) and \(x=-4-2(-7/5)=-4+14/5\)
\(x=-6/5\) 
Intersection point is 
\((-6/5,\,\,-7/5)\) . 
Now, the equation of the line which passes through the points 
\((0,0)\) and \((-6/5,\,-7/5)\) . 
\(y-y_1=\frac{y_2-y_1}{x_2-x_1}(x-x_1)\)
\(\Rightarrow\) \((y-0)+\frac{-7/5-0}{-6/5-0}(x-0)\)
\(\Rightarrow\) \(y=\frac{7}{6}.x\)
\(\Rightarrow\) \(7x=6y\)
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Concepts Used:

Straight lines

A straight line is a line having the shortest distance between two points. 

A straight line can be represented as an equation in various forms,  as show in the image below:

 

The following are the many forms of the equation of the line that are presented in straight line-

1. Slope – Point Form

Assume P0(x0, y0) is a fixed point on a non-vertical line L with m as its slope. If P (x, y) is an arbitrary point on L, then the point (x, y) lies on the line with slope m through the fixed point (x0, y0) if and only if its coordinates fulfil the equation below.

y – y0 = m (x – x0)

2. Two – Point Form

Let's look at the line. L crosses between two places. P1(x1, y1) and P2(x2, y2)  are general points on L, while P (x, y) is a general point on L. As a result, the three points P1, P2, and P are collinear, and it becomes

The slope of P2P = The slope of P1P2 , i.e.

\(\frac{y-y_1}{x-x_1} = \frac{y_2-y_1}{x_2-x_1}\)

Hence, the equation becomes:

y - y1 =\( \frac{y_2-y_1}{x_2-x_1} (x-x1)\)

3. Slope-Intercept Form

Assume that a line L with slope m intersects the y-axis at a distance c from the origin, and that the distance c is referred to as the line L's y-intercept. As a result, the coordinates of the spot on the y-axis where the line intersects are (0, c). As a result, the slope of the line L is m, and it passes through a fixed point (0, c). The equation of the line L thus obtained from the slope – point form is given by

y – c =m( x - 0 )

As a result, the point (x, y) on the line with slope m and y-intercept c lies on the line, if and only if

y = m x +c