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2006 AMC 10A Problem 2

Problem 2 of 25EasierAlgebra

Define xy=x3y.x \otimes y = x^3 - y. What is h(hh)?h \otimes (h \otimes h)?

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Solution

The inner operation gives hh=h3h.h \otimes h = h^3 - h. Then h(h3h)=h3(h3h)=h. \begin{aligned} h \otimes (h^3 - h) &= h^3 - (h^3 - h) \\ &= h. \end{aligned} Thus, the correct answer is C.

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Concepts: custom operation · algebraic manipulation

Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.