SOLUTION: Find the equation in slope-intercept form of the line through points (-2, 5) and (6, -15). Please give it step by step i want to know how to do this.

Algebra ->  Graphs -> SOLUTION: Find the equation in slope-intercept form of the line through points (-2, 5) and (6, -15). Please give it step by step i want to know how to do this.       Log On


   

Question 977238: Find the equation in slope-intercept form of the line through points (-2, 5) and (6, -15).
Please give it step by step i want to know how to do this.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Here is HOW to do that:

Known points on a line, (u,v) and (p,r).

If m is for slope of the line, then m=%28r-v%29%2F%28p-u%29.

Keeping in format of y=mx%2Bb for slope-intercept form,
solve this for b, and choose either of your given points.
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y-mx=mx%2Bb-mx
y-mx=b
b=y-mx
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Arbitrarily using (u,v) and using the formula for b,
b=v-m%2Au

Putting the whole slope-intercept form equation purely in symbolic form using the two assumed given points,
highlight%28y=%28%28r-v%29%2F%28p-u%29%29x%2Bv-%28%28r-v%29%2F%28p-u%29%29%2Au%29


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You do not really need to handle everything in complete symbolism. Just do this:

m=%28-15-5%29%2F%286-%28-2%29%29 and compute this.
Recall again the formula for the y-intercept, b=y-mx? Pick a given point and use the found slope m:
b=-15-%28-5%2F2%29%2A6 and compute this value of b.
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Now you know the value of m and the value of b.
Put them into y=mx+b.
DONE.



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b is actually 0, so your equation will simply be y=-%285%2F2%29x.