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UKMT Intermediate Mathematical Challenge, 2018

Algebra Difficulty 2.0 Junior Find the answer United Kingdom

For certain values of $x$ , the list $x$ , $x+6$ and $x^2$ contains just two different numbers. How many such values of $x$ are there?

(A) $1$ (B) $2$ (C) $3$ (D) $4$ (E) $5$

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