Question

How do you write an equation of the line containing the given point (3,4) and perpendicular to `y=3x+4`?

Answer 1

If it is perpendicular to `y=3x+4` then it has a gradient of `-1/3` because when you multiply the gradients together the answer is -1.

The line is of the form `y=-1/3x+c` but it passes through (3,4)

`=> 4=-1/3xx3+c`

`4=-1+c`

`c=5`

`y=-1/3x+5`