SOLUTION: I am supposed to find the zeros of {{{f(x)=3x^3-4x^2+8x+8}}} and I know there are going to be complex zeroes, I just do not know how to start factoring it so that I can solve it. M

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I am supposed to find the zeros of {{{f(x)=3x^3-4x^2+8x+8}}} and I know there are going to be complex zeroes, I just do not know how to start factoring it so that I can solve it. M      Log On


   



Question 1077099: I am supposed to find the zeros of f%28x%29=3x%5E3-4x%5E2%2B8x%2B8 and I know there are going to be complex zeroes, I just do not know how to start factoring it so that I can solve it. My textbook doesn't help much and I would truly appreciate the help.
Found 2 solutions by Edwin McCravy, Alan3354:
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
A potential zero is any positive or negative fraction 
whose numerator is a factor of 8 (the last term), and whose
denominator is a factor of 3 the leading coefficient.

So the potential zeros are positive or negative fractions 
with numerator 1,2,4, or 8 and denominator 1 or 3.

They are ±1,±1/3,±2,±2/3,±4,±4/3,±8,±8/3 

Try -2/3  and synthetic division.

If you have trouble, tell me in the thank-you note form 
below and I'll get back to you by email. (No charge ever).

Edwin


Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
I am supposed to find the zeros of f%28x%29=3x%5E3-4x%5E2%2B8x%2B8 and I know there are going to be complex zeroes, I just do not know how to start factoring it so that I can solve it.
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There are no integer factors.
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Look for a fractional zero as Edwin said.
Make an Excel sheet if you have it.
----------

3x^3-4x^2+8x+8	
	
-2	        -48
-1.666666667	-30.33333333
-1.333333333	-16.88888889
-1	        -7
-0.666666667	 0
-0.333333333	 4.777777778
0	         8
0.333333333	 10.33333333

-2/3 is a zero.
Divide by (3x+2), then solve the quadratic.