solve 2x^3 + 3x^2 - 5x + 6 = 0

oobleck oobleck answered

From Descartes' Rule of Signs, you know there is exactly one negative root.

The Rational Root Theorem and some synthetic division will soon show that it is not rational.
So you will need some numerical method to find it.
If you don't know any, a good place to start would be here:

keisan.casio.com/exec/system/1244946907