Question 1 of 5
A city installs a straight bike path along a road. On a map, the path is represented by a line. A sign at mile marker is located at the point , and a sign at mile marker is located at the point . City planners want to place a repair station at the point where the bike path crosses the -axis. Which equation can be used to find the -coordinate of the repair station?
Explanation
First find the slope of the line through and :
Using point-slope form with the point gives
so
Because the repair station is where the path crosses the -axis, its -coordinate is . Substitute :
which is equivalent to
Since , the equation is
Concept summary
To find where a linear graph crosses the -axis, write an equation of the line from two points and then set .