Which of the following could be equal to $x^{18}$ for an integer x?

Correct answer marked below

x^9 + x^9

(x^2)^9

(x^9)^9

(x^3)^{15}

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Explanation

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Official Explanation

Official

This is a classic "Could be" type trap: Here we need to reject only those answer options, which can never be equal to

x^{18}

for any integer x.

It can be seen that for x = 0 or 1, all answer options A, B, C, D are equal to

x^{18}

.…

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What this question tests

Your understanding of divisibility rules, least common multiples, and greatest common factors.

Forgetting that 1 is not prime and that every integer divides 0.