Monday

April 21, 2014

April 21, 2014

Posted by **Alyssa** on Saturday, July 25, 2009 at 10:29pm.

f(x) = 2x^3 – 3x^2 – 8x – 3.

(a) By using the Rational Zero Theorem, list all possible rational zeros of the given polynomial.

(b) Find all of the zeros of the given polynomial. Be sure to show work, explaining how you have found them.

- Algebra -
**Reiny**, Saturday, July 25, 2009 at 10:55pmvalues I would try are

±1, ±3, ±1/2, and ±3/2

b)

on the second try

f(-1) = -2-3+8-3 = 0

so x+1 is a factor.

by synthetic division I got

2x^3 – 3x^2 – 8x – 3 = (x+1)(2x^2 - 5x -3)

with a couple trial and error stabs, I factored the quadratic into (x-3)(2x+1)

so the factors are

(x+1)(x-3)(2x+1)

of course I could have continued with the above values of a) and tried

f(3), f(-3), f(1/2) etc

and would have found

f(3) and f(-1/2) also to result in zero.

- Algebra -
**Alyssa**, Saturday, July 25, 2009 at 11:05pmf(x)=0

F(x) = (2x+1) (x+1) (x-3)

x=-1/2

x=-1

x=3

F(x) =0

F(x) = (2x+1) (x+1) (x-3)

(2x+1) (x+1) (x-3) = 0

Is this a good way to show the procedure?

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