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a^2 = 3b^2. If 6b = 18, what is 2a^2?

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Math Expert
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Joined: 02 Sep 2009
Posts: 50058
a^2 = 3b^2. If 6b = 18, what is 2a^2?  [#permalink]

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New post 08 Feb 2017, 01:50
1
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A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

90% (00:43) correct 10% (00:54) wrong based on 63 sessions

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Posts: 6
Re: a^2 = 3b^2. If 6b = 18, what is 2a^2?  [#permalink]

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New post 08 Feb 2017, 01:55
Answer is B.
Given,
6*b=18,
b=3
Equation,
a^2 = 3*b^2 will yield
a^2=27

Required= 2*a^2= 54.
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Re: a^2 = 3b^2. If 6b = 18, what is 2a^2?  [#permalink]

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New post 08 Feb 2017, 07:39
Top Contributor
Bunuel wrote:
a² = 3b². If 6b = 18, what is 2a²?

A. 18
B. 54
C. 72
D. 108
E. 162


Given: 6b = 18
So, b = 3

Given: a² = 3b²
So, 2a² = 2(3b²) = 6b²
Replace b with 3 to get: 2a² = 6(3²) = 6(9) = 54

Answer: B
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Re: a^2 = 3b^2. If 6b = 18, what is 2a^2?  [#permalink]

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New post 08 Feb 2017, 14:51
6b = 18 => b=3
a^2 = 3b^2 = 3(3^2) = 27
Hence 2a^2 = 2*27 = 54 (Ans B)
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Re: a^2 = 3b^2. If 6b = 18, what is 2a^2?  [#permalink]

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New post 13 Feb 2017, 08:40
1
Bunuel wrote:
a^2 = 3b^2. If 6b = 18, what is 2a^2?

A. 18
B. 54
C. 72
D. 108
E. 162


We are given that 6b = 18; thus, b = 3. We are also given that a^2 = 3b^2; we can substitute b = 3 into the equation. So, we have:

a^2 = 3(3^2)

a^2 = 3 x 9

a^2 = 27

Thus, 2a^2 = 2 x 27 = 54.

Answer: B
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Re: a^2 = 3b^2. If 6b = 18, what is 2a^2? &nbs [#permalink] 13 Feb 2017, 08:40
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