What are all the possible rational zeros for f(x)=5x^3-2x^2+20x-8f(x)=5x32x2+20x8?

1 Answer
Oct 2, 2016

The possible rational zeros are: +-1, +-2,+-4,+-8,+-1/5,+-2/5, +-4/5, +-8/5±1,±2,±4,±8,±15,±25,±45,±85

Explanation:

Find the possible rational zeros of:

f(x)=color(red)5x^3-2x^2+2-x-color(blue)8f(x)=5x32x2+2x8

The possible rational zeros are found by dividing the factors of the constant term color(blue)88 (called color(blue)pp) by the factors of the leading coefficient color(red)55 (called color(red)qq).

color(blue)p/color(red)q=frac{+-1,2,4,8}{+-1,5}pq=±1,2,4,8±1,5

Dividing each number in the numerator by each number in the denominator gives:

+-1, +-2,+-4,+-8,+-1/5,+-2/5, +-4/5, +-8/5±1,±2,±4,±8,±15,±25,±45,±85