In order to simplify the given expression, identify like terms, bring them together using the commutative property and add their coefficients in order to combine them.
Remember that like terms are terms whose variables and their exponents are the same.
In the given expression:
The following terms are like terms:
3x² and 5x²
2x and -2x
-3 and 6
Then, change the order of the terms in the expression to bring like terms together:
Add the coefficients of like terms to combine them:
Since the coefficient of x is 0, we can discard the term 0x. Then, the expression is equal to:
Therefore, the final answer is: