Question

Find a rational zero of the polynomial function and use it to find all the zeros of the function. f(x) = x4 + 3x3 - 5x2 - 9x - 2

Answer 1

possible answers: http://prntscr.com/kvsbz

Answer 2

this might be easier to do if you try some of the answer choices

Answer 3

notice that there are a few differences in the options that would either make or break an option;

1, 2, and 3 if any of these makes a zero in the poly, then we know that option is correct, since none of the others contain them. If none of these provide a zero for us, then it has to be the remaining option

Answer 4

do we get a zero when x=1?

Answer 5

No, you get a 1... but I don't know what answer it is. >.<

Answer 6

well, we have two more numbers to test out

Answer 7

the one that works is the correct answer :)

Answer 8

Alright.

Answer 9

f(1) = 1^4 + 3(1)^3 - 5(1)^2 - 9(1) - 2
1 + 3 - 5 - 9 - 2
4 - 16
not equal 0 ; so x=1 is out

Answer 10

can you work this one for me?

f(2) = 2^4 + 3(2)^3 - 5(2)^2 - 9(2) - 2

Answer 11

so that means it's not A?

Answer 12

correct, it is not A

Answer 13

f(2)=0 ?

Answer 14

yes it does :) that means that our solution set HAS to have a +2 in it

Answer 15

so it's d?

Answer 16

i would say it is d yes; lets verify that with the wolf to be sure :)

Answer 17

http://www.wolframalpha.com/input/?i=+x4+%2B+3x3+-+5x2+-+9x+-+2%3D0

Answer 18

the wolf like it :)

Answer 19

:)

Answer 20

whenever i take a test that is multiple choice; then i know that one of the answers has to be correct; its just a matter of finding the most efficient way of weeding it out

Answer 21

http://prntscr.com/kvvan how do I do this one?