Question

3power x - 3powerx-2 equal to 72
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Answer 1

${3}^{x} - {3}^{x - 2} = 72 \\ \\ {3}^{x} (1 - {3}^{ - 2} ) = 72 \\ \\ {3}^{x} (1 - \frac{1}{9} ) = 72 \\ \\ {3}^{x} ( \frac{9 - 1}{9} ) = 72 \\ \\ {3}^{x} = 72 \times \frac{9}{8} = 81 \\ \\ {3}^{x} = 81 = {3}^{4}$

Therefore, x = 4.