find the equation of the line which satisfy the given condition: Passing through the points (–1, 1) and (2, – 4).
find the equation of the line which satisfy the given condition: Passing through the points (–1, 1) and (2, – 4).

Given:

 

Focuses \[\left( -\text{ }\mathbf{1},\text{ }\mathbf{1} \right)\text{ }\mathbf{and}\text{ }\left( \mathbf{2},\text{ }-\text{ }\mathbf{4} \right)\]

 

We realize that the condition of the line going through the focuses (\[\mathbf{x1},\text{ }\mathbf{y1})\text{ }\mathbf{and}\text{ }\left( \mathbf{x2},\text{ }\mathbf{y2} \right)\] is given by

NCERT Solutions for Class 11 Maths Chapter 10 – Straight Lines image - 15

\[\mathbf{y}\text{ }\text{ }\mathbf{1}\text{ }=\text{ }-\text{ }\mathbf{5}/\mathbf{3}\text{ }\left( \mathbf{x}\text{ }+\text{ }\mathbf{1} \right)\]

\[\mathbf{3}\text{ }\left( \mathbf{y}\text{ }\text{ }\mathbf{1} \right)\text{ }=\text{ }\left( -\text{ }\mathbf{5} \right)\text{ }\left( \mathbf{x}\text{ }+\text{ }\mathbf{1} \right)\]

\[\mathbf{3y}\text{ }\text{ }\mathbf{3}\text{ }=\text{ }-\text{ }\mathbf{5x}\text{ }\text{ }\mathbf{5}\]

\[\mathbf{3y}\text{ }\text{ }\mathbf{3}\text{ }+\text{ }\mathbf{5x}\text{ }+\text{ }\mathbf{5}\text{ }=\text{ }\mathbf{0}\]

\[\mathbf{5x}\text{ }+\text{ }\mathbf{3y}\text{ }+\text{ }\mathbf{2}\text{ }=\text{ }\mathbf{0}\]

The condition of the line is \[\mathbf{5x}\text{ }+\text{ }\mathbf{3y}\text{ }+\text{ }\mathbf{2}\text{ }=\text{ }\mathbf{0}.\]