Question

What s the equation of the line that passes through the points `(1, 2/3)` and `(-1, -1)`?

Answer 1

`y = 5/6 x - 1/6`

Explanation:

y - y1 = m ( x - x1 )

point 1 : ( 1 , 2/3 )
point 2: ( -1 , -1 )
The numbering of the points is arbitrary; just be consistent.

m can be solved as:
`( y2 - y1 ) / ( x2 - x1 )`

`m = ( -1 - 2/3 ) / ( -1 - 1 )`
`m = 5/6`

`y - 2/3 = 5/6 (x - 1)`
`y = 5/6 x - 5/6 + 2/3`
`y = 5/6 x - 1/6`

graph{y = 5/6 x - 1/6 [-6.21, 13.79, -1.64, 8.36]}