Question

How do you write an equation of a line with (2,3) ; (-1,4)?

Answer 1

I would use the following relationship involving the coordinates of your two points:
`(x-x_2)/(x_2-x_1)=(y-y_2)/(y_2-y_1)`
So:
`(x-(-1))/(-1-2)=(y-4)/(4-3)`
Giving:
`y=-1/3x+11/3`

Try substituting the coordinates of your points to check it.