To simplify the expression $7x^2 + x + 2x^2$, you need to combine the like terms.

1. Identify the like terms:

   • $7x^2$ and $2x^2$ are like terms because both contain $x^2$.
   • $x$ is a standalone term and cannot be combined with the others because it doesn't have $x^2$.

2. Combine the like terms:

   • $7x^2 + 2x^2 = 9x^2$

So the simplified expression is: $9x^2 + x$

Would you like further explanation on how to combine like terms or anything else? Here are some related questions you might find useful:

1. How do you identify like terms in algebraic expressions?
2. What is the difference between monomials, binomials, and polynomials?
3. How do you simplify expressions with variables raised to powers greater than 2?
4. What happens when you subtract like terms, and how does it compare to addition?
5. Can an expression be simplified if all terms are different powers of the same variable?

Tip: When simplifying expressions, always group and combine terms with the same variables and exponents!