Order of operations requires multiplication before addition: 3 × 4 = 12, then 2 + 12 = 14. The common error is computing 2 + 3 = 5 first, then 5 × 4 = 20 — but the expression means 2 + (3 × x), not (2 + 3) × x.
Question 2 True / False
In the expression 3x, the notation means the digit 3 is placed before the digit x to form a two-digit number (like thirty-something).
TTrue
FFalse
Answer: False
In algebra, 3x means 3 × x — three times the variable x. Letters are not digits; placing a number and a variable side by side indicates multiplication, not concatenation. If x = 5, then 3x = 15, not 35.
Question 3 Short Answer
What does it mean to evaluate the expression 5n − 3 when n = 2?
Think about your answer, then reveal below.
Model answer: Substitute 2 for n and apply order of operations: 5(2) − 3 = 10 − 3 = 7.
Evaluating an expression means replacing each variable with a given number and then computing the result. The variable is no longer a placeholder — it has a specific value — and standard arithmetic (following order of operations) gives the final answer.