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Mathematics

If 9n.32.3n(27)n33m.23=127\dfrac{9^n.3^2.3^n - (27)^n}{3^{3m}.2^3} = \dfrac{1}{27}, prove that m = 1 + n.

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Answer

Given,

9n.32.3n(27)n33m.23=127(32)n.32.3n(33)n33m.8=13332n+n.3233n33m.8=13333n.933n33m.8=13333n(91)33m.8=13333n.833m.8=3333n33m=3333n=33m.3333n=33m+(3)3n=3m33n=3(m1)n=m1m=1+n.\Rightarrow \dfrac{9^n.3^2.3^n - (27)^n}{3^{3m}.2^3} = \dfrac{1}{27} \\[1em] \Rightarrow \dfrac{(3^2)^n.3^2.3^n - (3^3)^n}{3^{3m}.8} = \dfrac{1}{3^3} \\[1em] \Rightarrow \dfrac{3^{2n + n}.3^2 - 3^{3n}}{3^{3m}.8} = \dfrac{1}{3^3} \\[1em] \Rightarrow \dfrac{3^{3n}.9 - 3^{3n}}{3^{3m}.8} = \dfrac{1}{3^3} \\[1em] \Rightarrow \dfrac{3^{3n}(9 - 1)}{3^{3m}.8} = \dfrac{1}{3^3} \\[1em] \Rightarrow \dfrac{3^{3n}.8}{3^{3m}.8} = 3^{-3} \\[1em] \Rightarrow \dfrac{3^{3n}}{3^{3m}} = 3^{-3} \\[1em] \Rightarrow 3^{3n} = 3^{3m}.3^{-3} \\[1em] \Rightarrow 3^{3n} = 3^{3m + (-3)} \\[1em] \Rightarrow 3n = 3m - 3 \\[1em] \Rightarrow 3n = 3(m - 1) \\[1em] \Rightarrow n = m - 1 \\[1em] \Rightarrow m = 1 + n.

Hence, proved that m = 1 + n.

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