SOLUTION: Find a Linear function whose graph passes through the given points. (8, -1) and (-5, 4) A. f(x) = -9/13x + 27/13 B. f(x) 5/13X = 27/13 C. f(x) 9/13x + 27/13 D. f(x)= - 5/13x

Algebra ->  Linear-equations -> SOLUTION: Find a Linear function whose graph passes through the given points. (8, -1) and (-5, 4) A. f(x) = -9/13x + 27/13 B. f(x) 5/13X = 27/13 C. f(x) 9/13x + 27/13 D. f(x)= - 5/13x      Log On


   

Question 22897: Find a Linear function whose graph passes through the given points.
(8, -1) and (-5, 4)
A. f(x) = -9/13x + 27/13
B. f(x) 5/13X = 27/13
C. f(x) 9/13x + 27/13
D. f(x)= - 5/13x = 27/13
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
First find the slope:
m=+%28rise%29%2F%28run%29
= %284-%28-1%29%29%2F%28-5-8%29
= 5%2F%28-13%29or %28-5%29%2F13

The only multiple choice that has a slope of -5/13 is D, so this must be the answer. However, just to make sure, let's find the y-intercept, by substituting everything you know into the formula y=mx+b, using x=8, y=-1, and m= -5/13.

y=mx+b
-1=%28%28-5%29%2F13%29%2A8+%2B+b

It might be easiest to clear the fraction by multiplying by the denominator which is 13:
13%2A%28-1%29+=+13%2A%28%28-5%29%2F13%29%2A8+%2B+13b
-13+=+-40+%2B+13b

Next, add 40 to both sides:
-13%2B+40+=+13b
27=13b

Divide both sides by 13:
27%2F13+=b

Final answer is
y=+%28%28-5%29%2F13%29x%2B+27%2F13

I think that is probably what you meant to write for the D answer.

R^2 at SCC