Question

Using complete sentences, explain how to find the zeros of the function f(x) = 2x3 – 9x + 3. Please help!!!

Answer 1

Anyone there?

Answer 2

i would find them by graphing or using a computer algebra system, but since the leading coefficient is 2 and the constant is 3 if you have a hope of finding rational zeros you have only a few choices

Answer 3

your choices are
\[\pm1,\pm3,\pm\frac{3}{2},\pm\frac{1}{2}\]

Answer 4

There isn't an exact way to solve it? with an equation or something?

Answer 5

unfortunately none of these work, and since i seriously doubt you want to use a formula i would just cheat.
there is a formula but you don't know it

Answer 6

it is not like the quadratic equation. it is long and complex

Answer 7

here is a picture with your answers
http://www.wolframalpha.com/input/?i=2x^3-9x%2B3%3D0

Answer 8

you can scroll down here to see the general formula for a cubic equation and you will see that you will not want to use it
http://en.wikipedia.org/wiki/Cubic_function

Answer 9

Thank you satellite73

Answer 10

if I have to create my own polynomial with a degree greater than 2 and find the zeros of the function how would I do that?

Answer 11

Maybe one that is easier.

Answer 12

write it out in factored form, then mulitply out. say you want the zeros to be -2, 3 and 1/2
the write out
\[(x+2)(x-3)(2x-1)\]

Answer 13

that obviously has zeros at -2, 3 and 1/2. multiply out to put it in standard form. i get
\[2 x^3-3 x^2-11 x+6\] but you can make up your own

Answer 14

just pick the zeros, write in factored form, and then multiply out. much easier than last problem, yes.

Answer 15

Okay so i have that equation you gave me, then you factor it out and is that it?

Answer 16

yup

Answer 17

Or which comes first making the equation or factoring it out

Answer 18

in other words work backwards. that is how your teacher makes up the problems.

Answer 19

1) write in factored form (don't show anyone)
2) multiply it out
3) factor again, you will get what you started with
4) now you know the zeros

Answer 20

How exactly would I show the work for this if I dont show that I factored it out i the beginning

Answer 21

U got it or not?

Answer 22

just factor. or else say "the only possible rational zeros are blah blah" check one and see that is works. then you can factor it out and you will have a quadratic, which you can solve using the quadratic formula, or by factoring since you know that it does

Answer 23

Okay so i wrote \[2x ^{3}-3x ^{2}-11x+6 \]

Answer 24

Then I wrote the factoring (x+2) (x-3) (2x-1)
Then I say the possible rational zeros are

Answer 25

-2, 3 and 1/2

Answer 26

thats fine

Answer 27

That is a good example of a polynomial
with a degree greater than 2 and the ze

ros of the function

Answer 28

*zeros

Answer 29

yes u r right

Answer 30

Thank you so much.

Answer 31

Well come most wellcome