posted by Carol .
The graph of the line through (2,3) that is perpendicular to the line with equation y= -1 also goes through which point?
Think about the line y=-1. What does it look like?
It's all the points where y is -1: (0, -1), (2, -1), (-2000, -1)... so it's a line straight up and down. Any line perpendicular to is must be straight across, so it must be of the form
x = something, where all the values of x are the same.
You know that the perpendicular passes through (2,3). What is the x value of that point?
So which of your choices has the same x-value?