What is the equation of the line between (-9,16)(−9,16) and (-4,12)(−4,12)?

1 Answer
Rachel
Apr 16, 2018

(-9,16)(−9,16) and (-4,12)(−4,12)

Let's use the point-slope formula

(y_2-y_1)/(x_2-x_1)y2−y1x2−x1

(12-16)/(-4--9)12−16−4−−9

(color(green)(-4))/color(blue)(5−45

Now we have the slope for point-slope form, which is y =mx+by=mx+b with mm being the slope and bb as the yy-intercept, the value of xx when y=0y=0

Let's guess:

y=-4/5x+5y=−45x+5
graph{y=-4/5x+5}

Were looking for (-4, 12)(−4,12)

Nope, not quite

y=-4/5x+5.2y=−45x+5.2
graph{y=-4/5x+5.2}

Almost

y=-4/5x+7.8y=−45x+7.8
graph{y=-4/5x+7.8}

We're so close

y=-4/5x+8.8y=−45x+8.8
graph{y=-4/5x+8.8}

Great! We have our equation!

y=-4/5x+8.8y=−45x+8.8

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