Step by step
The question
Question: are x = 3 and y = −2 parallel, perpendicular or neither.
The slopes tell us which.
Same slope: parallel.
Flip the slope and change its sign: perpendicular.
1 Slope of ①
x = 3 is a vertical line: straight up and down.
We call its slope undefined.
2 Slope of ②
There is no x term.
So m = 0: a flat line.
b is −2.
3 Compare the slopes
One line is vertical, the other is flat.
A vertical line and a flat line always meet at a square corner.
So the lines are perpendicular: they meet at a square corner.
4 Check
Let's see it on the grid.
Draw both lines.
They meet at a square corner.
Let's look back.
First: slope of ①.
Then: slope of ②.
Then: compare the slopes.
Last: check.