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| Author: | questioner [ Sat Feb 25, 2012 4:05 pm ] |
| Post subject: | GRE Algebra (Select One or More) |
If 20 – √x = 11, then what are possible values of x? -81, -9, 3, 9, 81 The correct answer is 81. Let's solve the equation 20 – √x = 11 by combining and rearranging. We get 9 = √x. Squaring both sides results in 81 = x, and this is the only value that x can take on. Thus, only answer 81 will be correct. ---------- -9 squared is also 81 is it not? |
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| Author: | Gennadiy [ Sat Feb 25, 2012 4:13 pm ] |
| Post subject: | Re: t.4, s.4, qt.10: equations, radicals |
Quote: -9 squared is also 81 is it not? (-9)² = 81 indeed, but the question is the inverse one.√x = 9, NOT x² = 81. |
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