How do you solve | x - 3 | = x + 1 graphically?

1 Answer
Jan 13, 2018

See explanation.

Explanation:

Look at the equation as two functions: y=abs(x-3) and y=x+1.

To graph y=abs(x-3) we know the the vertex is at (3,0). The slope to the right of the vertex is 1 and the slope to the right of the vertex is -1. The graph is piecewise linear. So graph y=-(x-3) for x<=3 and y=x-3 for x>3.

The graph of y=x+1 is a linear function with a y-intercept of (0,1) and x-intercept of (-1,0).

If you graph carefully enough you can see that the only intersection point is at (1,2), where the left branch of the absolute value, y=-(x-3) intersects the linear function, y=x+1.

Here's the graph.
graph{(y-abs(x-3))(y-x-1)=0 [-7.83, 12.17, -2.6, 7.4]}