Is x>0?

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Is x>0?

by BTGmoderatorDC » Sun Jun 26, 2022 10:59 pm

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Is x>0?

1) x^2=9x
2) x^2=81


OA C

Source: Veritas Prep

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Re: Is x>0?

by swerve » Mon Jun 27, 2022 10:07 am

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BTGmoderatorDC wrote:
Sun Jun 26, 2022 10:59 pm
Is x>0?

1) x^2=9x
2) x^2=81


OA C

Source: Veritas Prep
1) \(x^2=9x \Rightarrow x^2-9x =0 \Rightarrow x(x-9)=0\)
\(x\) can be \(0\) or \(9\). No Sufficient \(\Large{\color{red}\chi}\)

2) \(x^2=81 \Rightarrow x^2-81=0 \Rightarrow (x-9)(x+9)=0\)
\(x\) can be \(-9\) or \(9\). Not Sufficient \(\Large{\color{red}\chi}\)

Combining 1) and 2)
\(x\) is definitely \(9\). Sufficient \(\Large{\color{green}\checkmark}\)

Therefore, C