According to the Rational Root Theorem, if a polynomial equation has a rational root , then is a factor of the constant term and is a factor of the leading coefficient.
For the equation , the leading coefficient is 2 and the constant term is -4.
The factors of 2 are .
The factors of -4 are .
So the possible rational roots are .
Let's start testing these possible roots. Try .
Substituting into the equation:
=2 + 4 - 2 - 4
=6 - 2 - 4
=4 - 4
=0
So is a root.
Using synthetic division to divide the polynomial by