Question

find the slope of

x-1=2

Answer 1

x=3.slope is undefined as it is parallel to y axis

Answer 2

that is incorrect if it was a vertical line the slope would be undefined. The slope of the line x=3 is 0. Slope is rise / run. The reason a vertical line has an undefined slope is because it is rising but it runs 0. That means a 0 would be in the denominator. You can't divide by 0 so the slope is undefined.