Question

What is the equation of the line that passes through (1, 2) and (3, 4)?

Answer 1

`y=x+1`

Explanation:

`P_1=(1,2)`
`P_2=(3,4)`

The label of the points is arbitrary, just be consistent

`y-y_2=m(x-x_2)`

where:
`m=(y_2-y_1)/(x_2-x_1)`
`m=(4-2)/(3-1)`
`m=2/2`
`m=1`

`y-4=1(x-3)`
`y-4=x-3`
`y=x-3+4`
`y=x+1`

graph{x+1 [-9.45, 12.98, -2.53, 8.68]}