Question

3^n-3^n-1=18.explain. n=?

Answer 1

I understood the question like this. 

$3^{n} - 3^{n-1} = 18$

$3^{n} - \frac{3^{n}}{3} = 18$

Let $3^{n} = a$

Now the equation is $a - \frac{a}{3} = 18$

3a - a = 54

2a = 54

a = 27

$3^{n} = 27$

n = 3

Answer 2

Answer:

Step-by-step explanation:

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