Find, in the form of , the equation of the straight line that intercepts 20 length units from the negative part of the -axis and is perpendicular to the straight line whose equation is .
We know that equations for straight line graphs can be written in the form , where is the slope and is the -intercept.
First, rearrange into the form .
Comparing this equation to , we can see that the slope of the line is .
Then find the slope, , of the required line.
We know also that if 2 straight lines, and , having slopes and are perpendicular, then .
So, we know that .
The slope of the required line is , so its equation is
where is the -intercept.
Then find the -intercept.
We are told in the question that the line crosses the -axis at the point with coordinates . This point must satisfy the equation of the line, so we have
Substituting for in the equation gives us the equation of the required line.