Question 1052049: let f(x) = 4x^3+21x^2-x-84
a. factor f(x) given that 3 is a zero of f(x)
b. find the solution set for f(x)=0
Answer by josgarithmetic(39617)   (Show Source):
You can put this solution on YOUR website! Possible roots to check:
Numerator based on plus and minus of 1, 2, 3, 4, 6, 7, 12, 42, 84
Denominator based on plus and minus of 1, 2, 4
You WILL find that  used in synthetic division WILL give remainder of 0. I am omitting to show this work here, but you should try it yourself. You might also want to try some upper and lower bounds testing to see which roots you might be able to eliminate.
I used graphing software instead. Results look like  but you want to represent the original general form for f(x), so  .
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