Competition problem — Algebra — Maths Olympiad Prep

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Algebra Difficulty 1.4 Junior Find the answer

Which of the following expressions is not equivalent to $3x + 6$ ?

Your answer

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

Solution

We look at each of the five choices: (A) $3(x + 2) = 3x + 6$ (B) $\frac{-9x - 18}{-3} = \frac{-9x}{-3} + \frac{-18}{-3} = 3x + 6$ (C) $\frac{1}{3}(3x) + \frac{2}{3}(9) = x + 6$ (D) $\frac{1}{3}(9x + 18) = 3x + 6$ (E) $3x - 2(-3) = 3x + (-2)(-3) = 3x + 6$ The expression that is not equivalent to $3x + 6$ is the expression from (C).

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