SOLUTION: If f(x) = x^2 − 4x − 17and f(c) = 4,find c. (Enter your answers as a comma-separated list.)

Algebra ->  Equations -> SOLUTION: If f(x) = x^2 − 4x − 17and f(c) = 4,find c. (Enter your answers as a comma-separated list.)       Log On


   

Question 1127460: If f(x) = x^2 − 4x − 17and f(c) = 4,find c. (Enter your answers as a comma-separated list.)
Found 2 solutions by FrankM, josgarithmetic:
Answer by FrankM(1040) About Me  (Show Source):
You can put this solution on YOUR website!
This means 4 = x^2 − 4x − 17 and that you need to solve for x
subtract 4 from both sides.
x^2 − 4x − 21 = 0
factor

(x-7)(x+3) =0
x=7 x=-3
-3,7

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
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If f(x) = x^2 − 4x − 17and f(c) = 4,find c.
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c%5E2-4c-17=4
c%5E2-4c-17-4=0
c%5E2-4c-21=0
%28c-7%29%28c%2B3%29=0


c may be -3, or +7.