If 3x - 3x-1 = 18, then xx is equal to

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If 3^x - 3^x-1 = 18, then x^x is equal to

1. 3
2. 8
3. 27
4. 216

Correct Option: C

∵ 3^x - 3^{x - 1} = 18
⇒ 3^{x - 1}(3 - 1) = 18
⇒ 3^{x - 1}(2) = 18
⇒ 3^{x - 1} = 18/2
⇒ 3^{x - 1} = 9
⇒ 3^{x - 1} = 3²
Apply the Algebra law,
If a^X = a^Y then X will be equal to Y.
means X = Y;
⇒ x - 1 = 2
⇒ x = 3
Then x^x = (3)³ = 27