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# Is (6a + x^2)^(1/2) = a + x?

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Math Expert
Joined: 02 Sep 2009
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Is (6a + x^2)^(1/2) = a + x?  [#permalink]

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10 Sep 2017, 21:53
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Is $$\sqrt{6a + x^2} = a + x$$?

(1) x = 0
(2) a = 2

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Re: Is (6a + x^2)^(1/2) = a + x?  [#permalink]

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10 Sep 2017, 23:05
Bunuel wrote:
Is $$\sqrt{6a + x^2} = a + x$$?

(1) x = 0
(2) a = 2

Individually the statements are not going to be enough to prove
if $$\sqrt{6a + x^2} = a + x$$
as statement 1 contains the value of x and statement 2 contains the value of a

However, on combining the information from both the statements, we can clearly find out
that the equation $$\sqrt{6a + x^2} = a + x$$ is not true. (Sufficient) (Option C)
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Joined: 31 Jul 2017
Posts: 7
Re: Is (6a + x^2)^(1/2) = a + x?  [#permalink]

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18 Sep 2017, 20:01
But,
If a =2, then sqrt(6(2)+x) = 2+x
If you square both sides, 12+x^2 = 4+4x+x^2
subtract x^2, 12=4+4x
Thus, x =2.

So why can't the answer be just b?

pushpitkc wrote:
Bunuel wrote:
Is $$\sqrt{6a + x^2} = a + x$$?

(1) x = 0
(2) a = 2

Individually the statements are not going to be enough to prove
if $$\sqrt{6a + x^2} = a + x$$
as statement 1 contains the value of x and statement 2 contains the value of a

However, on combining the information from both the statements, we can clearly find out
that the equation $$\sqrt{6a + x^2} = a + x$$ is not true. (Sufficient) (Option C)
Math Expert
Joined: 02 Aug 2009
Posts: 6263
Re: Is (6a + x^2)^(1/2) = a + x?  [#permalink]

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18 Sep 2017, 20:34
akhan126 wrote:
But,
If a =2, then sqrt(6(2)+x) = 2+x
If you square both sides, 12+x^2 = 4+4x+x^2
subtract x^2, 12=4+4x
Thus, x =2.

So why can't the answer be just b?

pushpitkc wrote:
Bunuel wrote:
Is $$\sqrt{6a + x^2} = a + x$$?

(1) x = 0
(2) a = 2

Individually the statements are not going to be enough to prove
if $$\sqrt{6a + x^2} = a + x$$
as statement 1 contains the value of x and statement 2 contains the value of a

However, on combining the information from both the statements, we can clearly find out
that the equation $$\sqrt{6a + x^2} = a + x$$ is not true. (Sufficient) (Option C)

Hi..

We are not looking for value of x or a, we are to say if the two sides are EQUAL..
So you are correct if x=2, ans is YES..
But we don't know what is x, so if x is 0, and is NO..

Hope it helps
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Is (6a + x^2)^(1/2) = a + x?  [#permalink]

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23 Sep 2017, 22:59
Bunuel wrote:
Is $$\sqrt{6a + x^2} = a + x$$?

(1) x = 0
(2) a = 2

hi

The way I approached the DS is as under...

if both statements, taken together, the equation is clearly solvable...
however, to check whether any single value can solve the DS - as very often it can - it is very essential to simplify the question stem

After simplification, the stem looks like as under:

6a - a^2 = 2ax

here it is very clear that neither "a" nor "x" got cancelled out, so the magnitudes of 2 variables both are required to solve the DS...

please say to me whether the process I have followed is okay ...

Is (6a + x^2)^(1/2) = a + x? &nbs [#permalink] 23 Sep 2017, 22:59
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