Question

Find a rational zero of the polynomial function and use it to find all the zeros of the function
f(x) = x^4 + 3x^3 - 5x^2 - 9x - 2

A. {1, -2, -2 +(square root)3 , -2 - (square root)3}

B. {-1, -2, -2 +(square root ) 5 , -2 - (square root )5}

C. {-1, 3, -2 + (square root )5, -2 -(square root )5 }

D. {-1, 2, -2 +(square root )3 , -2 -(square root )3 }

Answer 1

If I am taking a test, and this is on the test, and I have forgotten how to find zeros of a polynomial, then knowing that a zero of the polynomial is an x-intercept -- an x value that sets f(x) = 0, and since I have been given some choices, I would just start plugging in and see what I get.

Guess what? I tried 2 (positive 2), and got a hit! And seeing that answer D is the only one with positive 2 as a possible answer, then the correct answer has to be D!

Answer 2

wow thank you so much @EulersEquation for your help :-)

Answer 3

Check the others. Negative one (-1) works as well. I would go with D and move on.

Answer 4

ok cool @EulersEquation

Answer 5

thanks again @EulersEquation

Answer 6

no prob. Thanks for the medal.

Answer 7

np prob