Question

Write the equation of the line passing through the points (0, -4) and (-2, 2).

Answer 1

Find slope.
\[m = \frac{ y2 - y1 }{ x2 - x1 }\]\[m = \frac{ 2 - (-4) }{ -2 - 0 } = \frac{ 2 + 4 }{ -2 - 0 } = \frac{ 6 }{ -2 } = -3\]Slope is -3.


You have the slope(-3) and you have a given point (0, -4).
Point-Slope form.
y - y1 = m(x - x1)

m is slope
Substitute the x- and y-values of your point, for x1 and y1.

So you have:\[y - (-4) = -3(x - 0)\]or\[y + 4 = -3(x - 0)\]
Change into Slope-Intercept form.
y = mx + b
\[y + 4 = -3(x - 0)\]Distribute. \[y + 4 = -3x - 0\]Solve for y.
Subtract 4 from both sides.\[y = -3x - 4\]^---There is your equation.

Answer 2

Hopefully this helped you understand the concept! (: