What is the value of 3n+3n−13n+1−3n?

C. 23 — 3n+3n−13n+1−3n=3n+3n313n×31−3n=3n1+133n3−1=432=46=23Put values of n as 0, 1, −1, ...... to get the answer.For n = 1 ; 3n+3n−13n+1−3n=31+3032−31=46=23

Number system — Question 4

SSC CGL · Quantitative Aptitude

$What is the value of (\frac{3^{n} + 3^{n}^{- 1}}{3^{n + 1} - 3^{n}}) ?$

Correct answer: C

$\frac{3^{n} + 3^{n - 1}}{3^{n + 1} - 3^{n}} = \frac{3^{n} + \frac{3^{n}}{3^{1}}}{3^{n} \times 3^{1} - 3^{n}}$

$= \frac{3^{n} (1 + \frac{1}{3})}{3^{n} (3 - 1)}$

$= \frac{\frac{4}{3}}{2} = \frac{4}{6} = \frac{2}{3}$

Put values of n as 0, 1, −1, ...... to get the answer.

For n = 1 ;

$\frac{3^{n} + 3^{n - 1}}{3^{n + 1} - 3^{n}} = \frac{3^{1} + 3^{0}}{3^{2} - 3^{1}} = \frac{4}{6} = \frac{2}{3}$

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Number system — Question 4

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