Thread: Solving Cubic Equations with p/q (Finding possible rational roots)

So here is the equation




After plugging in p/q and doing some basic algebra, we would get:



Now the book says the possible rational roots are ±1/3, ±2/3, ±1, ±2

I'm stuck on how to arrive the possible rational roots.

The rational roots theorem says that the possible rational roots of are formed from a factor of 2 divided by a factor of 3, with both negative and positive roots being possible. The factors of 2 are 1 and 2, and the factors of 3 are 1 and 3. This is where you get the eight possibilities .