Aline passes through the points (p, a) and (p, –a) where p and a are real numbers. if p=0, what is the y-intercept? explain your reasoning.

A line passes through the points (p, a) and (p, –a) where p and a are real numbers. If p=0, what is the y-intercept? Explain your reasoning. 

p - as "x" never changes with the value of "y", so no matter what y is, x is always "p", so when y is 0, x = p 

slope of the line 
change in y over the change in x 
(-a - a) / (p - p) = infinity - or a vertical line 
equation of the line 
y = p 
slope of a line perpendicular to the given line 
inverse of the orig slope or (p - p)/(-a - a) = 0