SOLUTION: find the equation of the line that has a slope of -8 and passes through the point (-1,-5) write the equation in standard form.

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Question 225449: find the equation of the line that has a slope of -8 and passes through the point (-1,-5) write the equation in standard form.
Answer by drj(1380) About Me  (Show Source):
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Find the equation of the line that has a slope of -8 and passes through the point (-1,-5) write the equation in standard form.

Step 1. The slope-intercept form is given as y=mx+b where m is the slope and b is the y-intercept when x=0 or at point (0,b). From the slope intercept form we can derive the standard form given as Ax+By=C where A, B, and C are constants. Now, let's find the equation of the line in slope-intercept form

Step 2. Here, we have to find the line with slope m=-8 going through point (-1,-5).

Step 3. Given two points (x1,y1) and (x2,y2), then the slope m is given as

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

Step 4. Let (x1,y1)=(-1,-5) or x1=-1 and y1=-5. Let other point be (x2,y2)=(x,y) or x2=x and y2=y.

Step 5. Now we're given m=-8. Substituting above values and variables in the slope equation m yields the following steps:

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

-8=%28y-%28-5%29%29%2F%28x-%28-1%29%29=%28y%2B5%29%2F%28x%2B1%29

Step 6. Multiply x+1 to both sides to get rid of denominator on right side of equation.

-8%28x%2B1%29=y%2B5

-8x-8=y%2B5

Step 7. Add -5 to both sides of the equation

-8x-8%2B%28-5%29=y%2B5%2B%28-5%29

-8x-13=y

Step 7. The equation in slope-intercept form is y=-8x-13 where the slope m=-8 and the y-intercept b=-13.

Note: the above equation can be rewritten in standard form by adding 8x to both sides of the equation.

-8x-13%2B8x=y%2B8x

8x%2By=-13

Step 8. ANSWER: The equation of the line in standard form is 8x%2By=-13.


And the graph is shown below which is consistent with the above steps.

graph%28600%2C600%2C-10%2C10%2C-20%2C10%2C-8x-13%29

I hope the above steps and explanation 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.

And good luck in your studies!

Respectfully,
Dr J
http://www.FreedomUniversity.TV