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What is x?

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What is x?

by VJesus12 » Thu May 03, 2018 10:48 am

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What is x? $$\left(1\right)\ \ \sqrt{4x}=6$$ $$\left(2\right)\ x^2=81$$ The OA is the option A.

Why is not sufficient the second statement? Any help?
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Source: — Data Sufficiency |

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by Jay@ManhattanReview » Thu May 03, 2018 6:57 pm

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VJesus12 wrote:What is x? $$\left(1\right)\ \ \sqrt{4x}=6$$ $$\left(2\right)\ x^2=81$$ The OA is the option A.

Why is not sufficient the second statement? Any help?
The second statement is not sufficient because of x^2 = 81 implies x = ±9. x can be either +9 or -9. No unique value. In the first statement, x cannot be negative, else the square root of 4x would be an imaginary number.

Hope this helps!

-Jay
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