# SSAT Upper Level Math : How to graph a function

## Example Questions

### Example Question #1 : How To Graph A Function

Refer to the above red line. A line is drawn perpendicular to that line, and with the same -intercept.  Give the equation of that line in slope-intercept form.

Explanation:

First, we need to find the slope of the above line.

The slope of a line. given two points  can be calculated using the slope formula

Set :

The slope of a line perpendicular to it has as its slope the opposite of the reciprocal of 2, which would be . Since we want this line to have the same -intercept as the first line, which is the point , we can substitute  and  in the slope-intercept form:

### Example Question #2 : Graphing Linear Functions

Refer to the above diagram. If the red line passes through the point , what is the value of ?

Explanation:

One way to answer this is to first find the equation of the line.

The slope of a line. given two points  can be calculated using the slope formula

Set :

The line has slope 3 and -intercept , so we can substitute  in the slope-intercept form:

Now substitute 4 for  and  for  and solve for :