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If x > 0, what is the value of x ?

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If x > 0, what is the value of x ?  [#permalink]

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New post 26 Jul 2017, 09:05
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Re: If x > 0, what is the value of x ?  [#permalink]

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Re: If x > 0, what is the value of x ?  [#permalink]

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New post 07 Dec 2017, 11:03
Dear Bunuel can you please clarify "^3√x=x, then x=x^3" how the interchange occurred? and I had x=1 in the statement 1 which made that sufficient, but what value do Statement 2 has to make it sufficient? Not getting this part in statement 2 "x^3–x=0. The same as in (1). Sufficient".
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Re: If x > 0, what is the value of x ?  [#permalink]

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New post 07 Dec 2017, 11:19
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sadikabid27 wrote:
Dear Bunuel can you please clarify "^3√x=x, then x=x^3" how the interchange occurred? and I had x=1 in the statement 1 which made that sufficient, but what value do Statement 2 has to make it sufficient? Not getting this part in statement 2 "x^3–x=0. The same as in (1). Sufficient".


(2) \(\sqrt[3]{x} - x = 0\)

\(\sqrt[3]{x} =x\)

Take to the third power: \(x = x^3\)

\(x^3 – x = 0\). Since x is not 0, we can safely reduce by x:

\(x^2 - 1 = 0\)

\(x^2 = 1\)

\(x = 1\) or \(x = -1\) (discard since \(x > 0\)).

So, \(x = 1\) only. Sufficient.
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Re: If x > 0, what is the value of x ?  [#permalink]

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New post 25 Oct 2018, 14:07
carcass wrote:
If x > 0, what is the value of x ?

(1) \(x^3 – x = 0\)

(2) \(\sqrt[3]{x} - x = 0\)



(DS17543)



This is basically Tautology in which the statements are repeated and yield the same answer.

\(x^3 - x = 0\)

\(x ( x^2 - 1) = 0\)

\(x ( x - 1) (x + 1) = 0\)

x > 0 so it can be -1 or 0 x = 1

For statement 2)

We square both sides we get \(x^3 - x = 0\)

Then the same goes on.

Answer choice D
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Re: If x > 0, what is the value of x ?   [#permalink] 30 Nov 2019, 07:18
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