What are the possible rational zeros of f(x) = x4 + 2x3 – 3x2 – 4x + 20 ?

1, 2, 4, 5, 10, 20
± 1, ± 2, ± 3, ± 4, ± 5, ± 6, ± 7, ± 8, ± 9, ± 10, ± 11, ± 12, ± 13, ± 14, ± 15, ± 16, ± 17, ±18, ± 19, ± 20
± 1, ± 2, ± 4, ± 5, ± 10, ± 20
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20

Question

What are the possible rational zeros of f(x) = x4 + 2x3 – 3x2 – 4x + 20 ?

    1, 2, 4, 5, 10, 20
    ± 1, ± 2, ± 3, ± 4, ± 5, ± 6, ± 7, ± 8, ± 9, ± 10, ± 11, ± 12, ± 13, ± 14, ± 15, ± 16, ± 17, ±18, ± 19, ± 20
    ± 1, ± 2, ± 4, ± 5, ± 10, ± 20
    1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20

barrycarter · Answer

Rational zeroes must divide 20 in this case. So, the divisors of 20.