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# Which of the following is equivalent to 21^(1/2)/6 ?

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Math Expert
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Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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09 Feb 2017, 04:57
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25% (medium)

Question Stats:

73% (01:09) correct 27% (01:33) wrong based on 235 sessions

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Which of the following is equivalent to $$\frac{\sqrt{21}}{6}$$?

A. $$\frac{\sqrt{7}}{2}$$

B. $$\sqrt{\frac{7}{2}}$$

C. $$\sqrt{\frac{7}{12}}$$

D. $$\frac{7}{\sqrt{6}}$$

E. $$\frac{21\sqrt{6}}{6}$$

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Re: Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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13 Feb 2017, 16:07
4
4
Bunuel wrote:
Which of the following is equivalent to $$\frac{\sqrt{21}}{6}$$?

A. $$\frac{\sqrt{7}}{2}$$

B. $$\sqrt{\frac{7}{2}}$$

C. $$\sqrt{\frac{7}{12}}$$

D. $$\frac{7}{\sqrt{6}}$$

E. $$\frac{21\sqrt{6}}{6}$$

Let’s simplify the given expression:

√(21)/6 = √(21)/√(36) = √(21/36) = √(7/12)

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##### General Discussion
VP
Joined: 05 Mar 2015
Posts: 1003
Re: Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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09 Feb 2017, 11:20
1
Bunuel wrote:
Which of the following is equivalent to $$\frac{\sqrt{21}}{6}$$?

A. $$\frac{\sqrt{7}}{2}$$

B. $$\sqrt{\frac{7}{2}}$$

C. $$\sqrt{\frac{7}{12}}$$

D. $$\frac{7}{\sqrt{6}}$$

E. $$\frac{21\sqrt{6}}{6}$$

multiply and divide by √21 to get 21/(6*√21)
or 7/2√21

or √49/√(4*21)

or √(49/84)

√7/12--------(dividing by 7)

Ans C
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Re: Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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09 Feb 2017, 12:24
√21/6, can be written as √21/(√4 * √9)

=> Cancelling out √3 from numerator and denominator, we get √7/(√4 * √3)

=> Above can be written as √7/√12

Therefore, Answer is C
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Re: Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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12 Apr 2017, 06:39
JeffTargetTestPrep wrote:
Bunuel wrote:
Which of the following is equivalent to $$\frac{\sqrt{21}}{6}$$?

A. $$\frac{\sqrt{7}}{2}$$

B. $$\sqrt{\frac{7}{2}}$$

C. $$\sqrt{\frac{7}{12}}$$

D. $$\frac{7}{\sqrt{6}}$$

E. $$\frac{21\sqrt{6}}{6}$$

Let’s simplify the given expression:

√(21)/6 = √(21)/√(36) = √(21/36) = √(7/12)

why you took denominator in root any particular reason
TIA
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Target#01 Q45,V20--April End

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Re: Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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12 Apr 2017, 07:05
ehsan090 wrote:
JeffTargetTestPrep wrote:
Bunuel wrote:
Which of the following is equivalent to $$\frac{\sqrt{21}}{6}$$?

A. $$\frac{\sqrt{7}}{2}$$

B. $$\sqrt{\frac{7}{2}}$$

C. $$\sqrt{\frac{7}{12}}$$

D. $$\frac{7}{\sqrt{6}}$$

E. $$\frac{21\sqrt{6}}{6}$$

Let’s simplify the given expression:

√(21)/6 = √(21)/√(36) = √(21/36) = √(7/12)

why you took denominator in root any particular reason
TIA

because you have to reduce the expresson
and we can reduce by cancelling factor 3 which is present in both num. & denominator
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Re: Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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12 Apr 2017, 07:18
Bunuel wrote:
Which of the following is equivalent to $$\frac{\sqrt{21}}{6}$$?

A. $$\frac{\sqrt{7}}{2}$$

B. $$\sqrt{\frac{7}{2}}$$

C. $$\sqrt{\frac{7}{12}}$$

D. $$\frac{7}{\sqrt{6}}$$

E. $$\frac{21\sqrt{6}}{6}$$

Square both Numerator and Denominator : $$\frac{21}{36}$$ => $$\frac{7}{12}$$

Since, we have taken square both in numerator and denominator, the actual value of the fraction will be : $$\sqrt{\frac{7}{12}}$$

Hence, answer must be (C) $$\sqrt{\frac{7}{12}}$$
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Manager
Joined: 08 Oct 2016
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Re: Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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12 Apr 2017, 23:47
[/quote]

why you took denominator in root any particular reason
TIA[/quote]

because you have to reduce the expresson
and we can reduce by cancelling factor 3 which is present in both num. & denominator [/quote]

Thanks mate a little clear. I need to practice these type of question for more clear understanding
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Joined: 11 Mar 2015
Posts: 35
Re: Which of the following is equivalent to 21^(1/2)/6 ?  [#permalink]

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16 Dec 2017, 08:04
√21/6
=√3*√7/3*2
=√7/√3*√4 as √4=2
=√7/√12
=√(7/12) Hence, Answer is C
Re: Which of the following is equivalent to 21^(1/2)/6 ? &nbs [#permalink] 16 Dec 2017, 08:04
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# Which of the following is equivalent to 21^(1/2)/6 ?

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