What to do
You are given two expressions that must have the same value. One term or coefficient is missing, and your job is to find what number makes the expressions equivalent.
Step-by-step method
- Read both expressions carefully. Identify the parts that are already known and the part that is missing.
- Use equivalence. Since the expressions are equal, set them equal if needed and compare like parts.
- Solve for the missing number.
- If a coefficient is missing, match the variable terms.
- If a constant is missing, match the numeric parts.
- If needed, use inverse operations to isolate the unknown.
- Substitute back. Replace the blank with your answer and check that both expressions now match.
- Simplify the final answer. If the result can be combined or reduced, write it in simplest form.
Helpful check
After finding the missing term, evaluate or expand both expressions to make sure they give the same result. If they do not, recheck signs, arithmetic, and whether the blank belongs to a term or a coefficient.