UP Police Constable Exam Model Paper 5

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Question : 92 of 150

Marks: +1, -0

If

2^{ {n}}-2^{ {n}-1}=4

, then the value of

{n}^{ {n}}

is equal to

8
9
27
None of these

Solution:

Given:

2^{ {a}}-2^{ {n}-1}=4

Calculation:

⇒ 2^{ {n}}-2^{ {n}-1}=4

⇒ 2^{ {n}}(1-2^{-1})=4

⇒ 2^{ {n} × \;{1}/{2}}=4

⇒ 2^{ {n}}=8=2^{3}

Then,

n=3

Hence,

{n}^{ {n}}=3^{3}=27

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