Question

Find the equation of a line that is parallel to the line x equals negative 1x=−1 and contains the point left parenthesis negative 2 comma 1 right parenthesis .

Answer 1

The equation of the line is given as $y-x=-1$

A straight line equation is given in the form $y=mx+c$ where $m$ is the gradient and $c$ is the y-interest.

We need to rearrange $y-x=-1$ to make $y$ the subject. 
$y= x-1$ ⇒ from here we can read the gradient and the y-intercept. The gradient, $m=1$ and $c=-1$.

A line that is parallel to $y=x-1$ will have the same gradient, $m=1$ but different y-intercept. One example of equation of a line that is parallel to $y=x-1$ is $y=x+3$