Question

Find an equation of the line that goes through the points (2, -8) and(-1, 1). Write your answer in slope-intercept form.

Answer 1

y = -3x - 2

Explanation:

As we move to the right from (-1, 1) to (2, -8), x increases by 3 and y decreases by 9. Hence, the slope of this line is m = rise / run = -9/3 = -3.

Start with the general slope-intercept form: y = mx + b.

Substitute -8 for y, 2 for x and -3 for m:

-8 = -3(2) + b

So, b = -2, and the desired equation is y = -3x - 2. Note that (-1, 1) satisfies this equation.

Answer 2

y = -3x + 14

Explanation:

Gradient

= (1 - (-8))/(-1 - 2)

= 9/(-3)

= -3

y - intercept

= -8 + 3(2)

= 8 + 6

= 14

Equation

y = -3x + 14