## Algebra: A Combined Approach (4th Edition)

The graph of x=1 has a vertical line with x-intercept 1. Find pair solutions of x=1. We let (x1,y1)=(1,0) and (x2,y2)=(1,1) m=$\frac{1-0}{1-1}$=$\frac{1}{0}$ Since $\frac{1}{0}$ is undefined, the slope of x=1 is undefined