SOLUTION: Find the equation of the line that contains the points P1(–8, –12) and P2(9, –12).

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Question 225022: Find the equation of the line that contains the points P1(–8, –12) and P2(9, –12).
Answer by drj(1380) About Me  (Show Source):
You can put this solution on YOUR website!
Find the equation of the line that contains the points P1(–8, –12) and P2(9,–12).

Step 1. We will put the equation of the line in slope-intercept form given as y=mx+b where m is the slope and b is the y-intercept when x=0 or at point (0,b).

Step 2. The slope of the line m is given as

+m=%28y2-y1%29%2F%28x2-x1%29

where for our example is x1=-8, y1=-12, x2=9 and y2=-12 (think of slope=rise%2Frun). You can choose the points the other way around but be consistent with the x and y coordinates. You will get the same result.

Step 3. Substituting the above values in the slope equation gives

m=%28-12-%28-12%29%29%2F%289-%28-8%29%29

m=0%2F17=0

Step 4. The slope is calculated as 0 or m=0

Step 5. Now use the slope equation of Step 2 and choose one of the given points. I'll choose point (9,-12). Letting y=y2 and x=x2 and substituting m=0 in the slope equation given as,

+m=%28y2-y1%29%2F%28x2-x1%29


+0=%28y-%28-12%29%29%2F%28x-9%29

+0=%28y%2B12%29%2F%28x-9%29

Step 6. Multiply both sides of equation by x-9 to get rid of denominator found on the right side of the equation


+%28x-9%29%2A0=%28x%2B12%29%28y-2%29%2F%28x-9%29

0=y%2B12

y=-12

Step 9. ANSWER: The equation of the line is y=-12


See graph below to check the above steps.

Solved by pluggable solver: DESCRIBE a linear EQUATION: slope, intercepts, etc
This equation defines a horizontal line. There is no X intercept. Y intercept is -12%2F1=-12
graph%28+500%2C+500%2C+-10%2C+10%2C+-12+-+10%2C+-12%2B10%2C+-12%2F1+%29+



I hope the above steps were helpful.

For FREE Step-By-Step videos in Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra and for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.

Good luck in your studies!

Respectfully,
Dr J