1. **State the problem:** Simplify the expression $3x^2 - x + 6$. 2. **Identify the terms:** The expression consists of three terms: $3x^2$ (quadratic term), $-x$ (linear term), and $6$ (constant term). 3. **Check for like terms:** There are no like terms to combine since each term has a different power of $x$. 4. **Final expression:** The expression is already simplified as $3x^2 - x + 6$. This is a quadratic expression in standard form.