Question 26595: The directions say to find the equation of the line passing through the given points, use function notation.
(8,-3), (4,-8)
i'm not sure what to do, please help, thanks
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! the straight line will have the form y=mx+c or in function notation, f(x) = mx+c.
We need the gradient, m first.
m = (change in y)/(change in x)
m = (-8 - -3)/(4 - 8)
m = (-8 + 3)/(4 - 8)
m = (-5)/(-4)
m = 5/4
so, f(x) = (5/4)x + c
Now for c... we need to know x and y. We do...we have 2 versions to use --> the 2 sets of coordinates. Pick one pair...the easiest looking. Here, God knows, so just pick one. I pick (8,-3)
-3 = (5/4)(8) + c
-3 = 5*2 + c
-3 = 10 + c
--> c = -13
so, the function is f(x) = (5/4)x - 13
jon.
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