Math question: write the equation of the line with an undefined slope, passing through the point (2, 5).

When an equation has a line with an undefined slope, it means that the line is vertical. 

(2,5); 2 is the x - coordinate and 5 is the y - coordinate

Slope -  intercept form: y = mx + b

As shown above, the equation would've been written in slope - intercept form, where 'm' represents the slope and 'b' represents the y - intercept. However, in this case, the slope is undefined.
In the equation, you are ONLY looking for the x - intercept. Therefore, the x - intercept is 5, so that may be the equation of the line.

x = 5