When you’re working with algebraic expressions, it’s super easy to make some common mistakes. Here are a few important ones to be careful about:

1. Remembering the Order of Operations: Always use PEMDAS! This stands for Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction. For example, in the expression $3 + 4 \times 2$, you should do the multiplication first. So, you get $4 \times 2 = 8$. Then, add it to $3$. The right answer is $3 + 8 = 11$. It’s not $7 \times 2 = 14$!

2. Using the Wrong Numbers: Make sure to check the numbers you're putting into your expression. It’s easy to accidentally replace $x$ with the wrong value.

3. Not Paying Attention to Negative Signs: Watch out for negatives! If your expression is $-x + 5$ and you use $3$ for $x$, don’t forget it’s not just $-3 + 5$. It really is $-3 + 5 = 2$.

4. Skipping Simplification: After replacing values, don’t forget to simplify your expression to find the final answer.

By keeping these tips in mind, you’ll find that evaluating algebraic expressions becomes much easier!