SOLUTION: The Compass practice test question is 'What is the equation of the line that contains the points with (x,y) coordinates (-3,7) and (5,-1')? I know the answer is y=x+4 but how do yo

Question 623042: The Compass practice test question is 'What is the equation of the line that contains the points with (x,y) coordinates (-3,7) and (5,-1')? I know the answer is y=x+4 but how do you go about getting that answer? Is there an easy formula to figure it out? Please show me step by step...
Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
Formula? No, I don't think so!
Here's one way to get the answer.
Start with:
y = mx+b Find the slope, m:
The x's and y's are the coordinates of the two given points, so we substitute:
Evaluate.

so now you have:
y = -x+b To find b, substitute the x- and y-coordinates of either of the two given points. Let's choose (-3, 7) and substitute:
7 = -1(-3)+b Solve for b.
7 = 3+b Subtract 3 from both sides.
b = 4
The final equation is:
y = -x+4
Your answer is almost correct but you'll find that the slope, m, is negative!
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