Question

The equation of the line that goes through the points ( − 3 , − 9 ) and ( − 6 , − 3 ) can be written in the form y = m x + b

Answer 1

`y=-2x-15`

Explanation:

`y=mx+b`.

m is the slope of the line. To find it we can do
`(dy)/(dx)` which is the difference between the y-coordinates divided by the difference between the x-coordinates.

So:
`(dy)/(dx) =(-9-(-3))/(-3-(-6)) =(-6)/(3) =-2`. Now we have the slope, let's input a set of coordinates into the equation so that we can find the constant
`b`.

`-9=-2(-3)+b`

`b=-15` - Re-arranging to get b

Now re-write the equation as we have the constants.

`y=-2x-15`