Watch with Theo · Checking answers
ACT Math: Answer the Quantity the Question Actually Asks For
Solve for the variable, then return to the exact quantity the question requests.
Take this into your next practice session
Check the requested quantity, sign, and units before selecting an answer.
Choose an answer, then check your reasoning. This public practice is not saved.
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4: First add 2 and divide by 5. Then square the value of x; finding x alone is not the final step.
16 — correct answer: Correct. 5x = 20, so x = 4. The requested value is x² = 16.
20: First add 2 and divide by 5. Then square the value of x; finding x alone is not the final step.
36: First add 2 and divide by 5. Then square the value of x; finding x alone is not the final step.
Full transcript and worked example
Answer the question they asked.
Hi, I'm Theo. You can do the algebra correctly and still select the wrong answer. The key is to check what the question actually asks for. Here we need three x, not just x.
If 2x + 3 = 11, what is 3x?
Solve for the variable.
Subtract three from both sides to get two x equals eight. Divide by two, and x is four. Four appears among the choices, but we are not finished.
2x = 8 → x = 4
Return to the target.
The question asks for three x. Substitute four and multiply by three. The answer is twelve, choice C. Four was only an intermediate result.
3x = 3(4) = 12
Use a short final check.
Before selecting an answer, check the requested quantity, the sign, and any units. If a question asks for area, a length is not enough. Make the check brief and specific to the problem.
Quantity → sign → units
Your turn.
Now try five x minus two equals eighteen. The question asks for x squared. Solve for x, then take the extra step. Which value answers the actual question?
If 5x − 2 = 18, what is x²?
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