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Moderator  Joined: 18 Apr 2015
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Define x* by the equation x* = π/x. Then ((–π)*)* = [#permalink]
Expert's post 00:00

Question Stats: 64% (00:26) correct 35% (01:02) wrong based on 14 sessions
Define $$x^*$$ by the equation $$x^* = \frac{\pi}{x}$$. Then $$((-\pi)^*)^*$$ =

A. $$\frac{-1}{\pi}$$

B. $$\frac{-1}{2}$$

C. $$- \pi$$

D. $$\frac{1}{\pi}$$

E. $$\pi$$
[Reveal] Spoiler: OA

_________________ Manager  Joined: 15 Jan 2018
Posts: 147
GMAT 1: Q V
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Re: Define x* by the equation x* = π/x. Then ((–π)*)* = [#permalink]
1
KUDOS
In a problem like this, simply do a find and replace with the x into whatever the function is. In this case, every time you see an *, replace whatever is under it with the x in the given function. Since this one is nested in two sets of parenthesis, let's do the inside set first.

The inside-most function is -π*, so we should replace the x in the given function with -π. Thus, we get:

π/-π = -1

Now, the outer-most function is whatever result we got from the last function. So we have -1*. Repeat:

π/-1 = -π

So the answer is C.
_________________

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Need help with GRE math? Check out our ground-breaking books and app. Re: Define x* by the equation x* = π/x. Then ((–π)*)* =   [#permalink] 04 Apr 2018, 20:20
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