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

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

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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. \(\frac{21\sqrt{6}}{6}\)
[Reveal] Spoiler: OA

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

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New post 09 Feb 2017, 11:20
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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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New post 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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New post 13 Feb 2017, 16:07
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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)

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

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New post 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)

Answer: C


why you took denominator in root any particular reason
TIA
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Re: Which of the following is equivalent to 21^(1/2)/6 ? [#permalink]

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New post 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)

Answer: C


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

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New post 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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Re: Which of the following is equivalent to 21^(1/2)/6 ?   [#permalink] 12 Apr 2017, 23:47
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