If a is a positive integer, then 3^a + 3^(a +1) = : Problem Solving (PS)

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Bunuel

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If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

03 Dec 2014, 08:24

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A

B

C

D

E

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82% (00:52) correct

18% (01:07) wrong

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Tough and Tricky questions: Exponents.

If a is a positive integer, then 3^a + 3^(a +1) =

A) 4^a
B) 3^a − 1
C) 3^(2a) + 1
D) 3^a*(a − 1)
E) 4(3^a)

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omegacube

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

Updated on: 03 Dec 2014, 21:18

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3^a + 3^(a +1)
= 3^a + 3.3^a
= 3^a(1 + 3)
= 4(3^a)

Hence E

Originally posted by omegacube on 03 Dec 2014, 08:33.
Last edited by omegacube on 03 Dec 2014, 21:18, edited 1 time in total.

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

03 Dec 2014, 12:32

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3^a + 3^(a+1) = 3^a + 3^a*3 = 3^a(1+3) = 4*3^a.

Choice E

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

03 Dec 2014, 13:55

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3^a+3^(a+1)
Factor: 3^a(1+3) (because 3^a times 1 is 3^a, and 3^a times 3 is 3^(a+1))
Simplify: 4(3^a)

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

03 Dec 2014, 21:17

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Answer = E) 4(3^a)

$3^a + 3^{(a +1)} = 3^a + 3^a * 3 = 3^a (1 + 3) = 4 * 3^a$

JJo

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

03 Dec 2014, 21:43

3^a + 3^(a +1)
= 3^a + (3^a * 3^1)
= 3^a (1 + 3)
= 3^a(4)

Ans. E) 4(3^a)

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

30 Jan 2017, 14:34

$3^{a} + 3^{a+1}$
$3^{a} + 3^{a} . 3^{1}$
$3^{a}$ x (1 + 3)
$3^{a}$x(4)
E

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

30 Jan 2017, 23:57

3^a + 3^(a +1)
= 3^a + 3.3^a
= 3^a(1 + 3)
= 4(3^a)

Hence E

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If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

02 Feb 2017, 12:21

Expert Reply

Bunuel wrote:

Tough and Tricky questions: Exponents.

If a is a positive integer, then 3^a + 3^(a +1) =

A) 4^a
B) 3^a − 1
C) 3^(2a) + 1
D) 3^a*(a − 1)
E) 4(3^a)

3^a + 3^(a +1)

3^a + (3^a)(3^1)

3^a(1 + 3^1)

3^a(4)

Answer: E
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sjavvadi

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

02 Feb 2017, 12:25

3^a+3^(a+1)
=3^a+3^a.3
=3^a(1+3)
=3^a.4

Hence (E)

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

05 May 2017, 12:39

If a is a positive integer, then $3^a$ + $3^{(a +1)}$ =

$3^a$ + $3^ {(a+1)}$
= $3^a$ + $3^a$ * $3^1$
= $3^a$ (1 + 3)
= $3^a$ * 4 = 4($3^a$)

Therefore Answer E...

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Re: If a is a positive integer, then 3^a + 3^(a +1) = [#permalink]

05 May 2017, 12:39

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