Question

Use the Rational Zeros Theorem to write a list of all possible rational zeros of the function. -2x^4+4x^3+3x^2+18

Answer 1

let f(x) = 2x^4 + 4x^3 + 3x^2 + 18
f(1) = 2+4+3+18 ≠ 0
f(-1) = 2 - 4 + 3 + 18≠0
f(2) ≠0
f(-2) ≠0
...
f(±9) ≠ 0

tried ±1, ±2, ±3, ±6, ±9, ±1/2, ± 3/2, ±9/2
none worked

could not find any rational factors

Answer 2

here is a nice youtube showing how it works

http://www.youtube.com/watch?v=hJCHhWlyIws