Find the equation of the line parallel to y-axis and drawn through the point of intersection of the lines x – 7y + 5 = 0 and 3x + y = 0.
Find the equation of the line parallel to y-axis and drawn through the point of intersection of the lines x – 7y + 5 = 0 and 3x + y = 0.

Here the situation of any line corresponding to the y-pivot is of the structure

 

    \[\mathbf{x}\text{ }=\text{ }\mathbf{a}\text{ }\ldots \text{ }.\text{ }\left( \mathbf{1} \right)\]

Two given lines are

 

    \[\mathbf{x}\text{ }\text{ }\mathbf{7y}\text{ }+\text{ }\mathbf{5}\text{ }=\text{ }\mathbf{0}\text{ }\ldots \text{ }\left( \mathbf{2} \right)\]

    \[\mathbf{3x}\text{ }+\text{ }\mathbf{y}\text{ }=\text{ }\mathbf{0}\text{ }\ldots \text{ }\left( \mathbf{3} \right)\]

By addressing conditions (2) and (3) we get

 

    \[\mathbf{x}\text{ }=\text{ }-\text{ }\mathbf{5}/\mathbf{22}\text{ }\mathbf{and}\text{ }\mathbf{y}\text{ }=\text{ }\mathbf{15}/\mathbf{22}\]

 

    \[\left( -\text{ }\mathbf{5}/\mathbf{22},\text{ }\mathbf{15}/\mathbf{22} \right)\]

is the mark of convergence of lines (2) and (3)

 

In the event that the line

    \[\mathbf{x}\text{ }=\text{ }\mathbf{a}\]

goes through point

    \[\left( -\text{ }\mathbf{5}/\mathbf{22},\text{ }\mathbf{15}/\mathbf{22} \right)\]

 we get

    \[\mathbf{a}\text{ }=\text{ }-\text{ }\mathbf{5}/\mathbf{22}\]

Consequently, the necessary condition of the line is

    \[\mathbf{x}\text{ }=\text{ }-\text{ }\mathbf{5}/\mathbf{22}.\]