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\(\oplus\) and \(\odot\) are two operators on numbers p and q such that

\(p \oplus q = \frac{p^{2} + q^{2}}{pq}\) and \(p \odot q = \frac{p^{2}}{q}\);

If \(x \oplus y = 2 \odot 2\), then x =

  • A.\(\frac{y}{2}\)
  • B.y
  • C.\(\frac{3y}{2}\)
  • D.2 y

Answer: B

The answer is x = y.

First evaluate the right-hand side: \(2 \odot 2 = \frac{2^{2}}{2} = 2\). Then

\[ \begin{aligned} \frac{x^{2} + y^{2}}{xy} &= 2 \\ x^{2} - 2xy + y^{2} &= 0 \\ (x - y)^{2} &= 0 \end{aligned} \]

so x = y. Checking a distractor: with x = 2y the left side is (4 + 1)/2 = 2.5, and with x = y/2 it is also 2.5, not 2; x = 3y/2 gives 13/6. Only x = y makes the sum of squares equal to twice the product.

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