Question

Write an equation of the line passing through the points (3,9) and (-1,-15).
I

Answer 1

y = 6x - 9

Explanation:

equation of line y = mx + b

lets find the slope m = (y2-y1)/(x2-x1):

m = ((-15)-9)/((-1)-3)

m = 6

let's plug this into our equation:

y = 6x + b

now we can plug in a point, I choose (3,9)

9 = 6(3) + b

b = -9

lets plug everything into our equation

y = 6x - 9