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31 Dec 2017, 12:10
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
76% (01:14) correct
24%
(01:58)
wrong
based on 74
sessions
History
Date
Time
Result
Not Attempted Yet
Is rst = 1 ?
(1) \(r\sqrt{t} =\frac{s\sqrt{t}}{s}\)
(2) \(\frac{rt}{\sqrt{t}}=\frac{\sqrt{t}}{st}\)
(1) \(r\sqrt{t} =\frac{s\sqrt{t}}{s}\)
(2) \(\frac{rt}{\sqrt{t}}=\frac{\sqrt{t}}{st}\)
31 Dec 2017, 14:23
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Bunuel
As this looks to be a very technical question (with many equations), we'll just solve it.
This is a Precise approach.
(1) We can cancel out \(s\) from the right-hand side giving \(r\sqrt{t} =\sqrt{t}\)
As we don't know if \(t = 0\) or not, we can't cancel it out but we can rewrite as \(r\sqrt{t} -\sqrt{t}=0\)
This simplifies to \(\sqrt{t}(r-1)=0\) meaning that \(t = 0\) or \(r = 1\).
Insufficient!
(2) Since both \(s\) and \(t\) are in the denominator, they can't be equal to 0 so we can multiply by them.
Multiplying by \(s\) and by \(\sqrt{t}\) gives \(rst = \frac{t}{t}=1\)
Sufficient!
(B) is our answer.
29 Jan 2018, 14:22
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DavidTutorexamPAL
Can you please explain how you multiplied (2)? Cross multiply?
"2) Since both ss and tt are in the denominator, they can't be equal to 0 so we can multiply by them.
Multiplying by ss and by t√t gives rst=tt=1rst=tt=1
Sufficient!" I'm not seeing it, thanks.
