3^3乘9^n乘27^n-2=3^47,求2n+5的值

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3^3乘9^n乘27^n-2=3^47,求2n+5的值
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3^3乘9^n乘27^n-2=3^47,求2n+5的值
3^3乘9^n乘27^n-2=3^47,求2n+5的值

3^3乘9^n乘27^n-2=3^47,求2n+5的值
3^3×9^n×27^(n-2)
=3^3×3^(2n)×3^[3(n-2)]
=3^[3+2n+3(n-2)]
=3^(5n-3)
=3^47
5n-3=47==>n=10
2n+5
=2×10+5
=25