Question

What is an equation of the line that passes through the point (3,-1) and (8, 9)?

1) y = 2x + 5
2) y = 2x - 1
3) y = 2x - 4
4) y = 2x - 7

Answer 1

4) y = 2x - 7

Explanation:

First we have to find the slope by using the following formula....

let (3, - 1) be
`(x_(1), y_(1) )`, let (8, 9) be
`(x_(2) ,y_(2) )`, and m be the slope, then....

`m = (y_(2) -y_(1) )/(x_(2) - x_(1) ) = (9 + 1)/(8 - 3) = (10)/(5) = 2`

Now that we know the slope we can find the equation of the function by using point-slope for of the function which look like this.....

`y -y_(1) = m(x - x_(1) )\\y + 1 = 2(x - 3)\\y + 1 = 2x - 6\\y = 2x - 7`