Algebra practice question

Answer: 4

Expand: ax − 3a = 4x − 12. For this to hold for every x, the x-coefficients must match (a = 4) and the constants must match (−3a = −12, also a = 4).

Common wrong answers

If you answered 3

3 is the number subtracted inside the parentheses, not the multiplier.

If you answered 12

12 is the constant on the right; the multiplier a satisfies 3a = 12, so a = 4.

If you answered -4

−4 would give −4x + 12 on the left, the negative of the right side.

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