How do you write the equation in point slope form given (5,-8) , (-9,-8)?

Question

3221 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-03-14T13:04:05

$(y + color(red)(8)) = color(blue)(0)(x - color(red)(5))$

Or

$(y + color(red)(8)) = color(blue)(0)(x + color(red)(9))$

Or

$(y + color(red)(8)) = color(blue)(0)(x + color(red)(a))$ Where $a$ is any value you want.

Because both points have the same $y$ value of $-8$ we know by definition this is a horizontal line with a slope of $m = 0$ .

The point-slope formula states: $(y - color(red)(y_1)) = color(blue)(m)(x - color(red)(x_1))$

Where $color(blue)(m)$ is the slope and $color(red)(((x_1, y_1)))$ is a point the line passes through.

Substituting the slope and the first point from the problem gives:

$(y - color(red)(-8)) = color(blue)(0)(x - color(red)(5))$

$(y + color(red)(8)) = color(blue)(0)(x - color(red)(5))$

We can also substitute the slope and the second point from the problem giving:

$(y - color(red)(-8)) = color(blue)(0)(x - color(red)(-9))$

$(y + color(red)(8)) = color(blue)(0)(x + color(red)(9))$