Question

How do you write an equation of a line through (-3,1) and perpendicular to y= -3x+7?

Answer 1

`y=1/3x+2`

Explanation:

The gradient of `y=-3x+7` is -3
The gradient of a line perpendicular is `1/3`
To prove this to yourself draw a line with gradient -3 on squared paper and the draw a line at right angles

So the line of the perpendicular will be in the form
`y=1/3x +c`
But we know it goes through (-3,1)
So substituting those values gives
`1=1/3*-3+c`
1=-1+c
c=2