Ok, math whizzes, explain this one

[Armymutt25A]

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The comparison is this:
For all numbers n, n* = 32-n. Which is greater? (n*)* or n?

Does the * represent something other than an exponent? All the explanations I can find go like this:
(n*)*=32-n*
=32-(32-n)
=32-32+n
=n

I don't recall any rule that says that an exponent doesn't affect both sides of the equation equally i.e. it should be (n*)*=(32-n*)*, which is very different than the above calculation. Apparantly, the above is correct though, so I'd like to know why.

 

[SilverSpyderGT]

The comparison is this:
For all numbers n, n* = 32-n. Which is greater? (n*)* or n?

Does the * represent something other than an exponent? All the explanations I can find go like this:
(n*)*=32-n*
=32-(32-n)
=32-32+n
=n

I don't recall any rule that says that an exponent doesn't affect both sides of the equation equally i.e. it should be (n*)*=(32-n*)*, which is very different than the above calculation. Apparantly, the above is correct though, so I'd like to know why.

Is this GRE prep?

The "*" is just a symbol that's telling you to do something to n (in this case, subtract n from 32).

If n = 3, then n* = 29 (n* = 32 - n = 32 - 3 = 29).

(n*)* means that you do whatever thing n* means again. So if n* means subtract n from 32, then (n*)* means subtract n from 32, and then subtract your new number from 32.

(n*)* = (32 - n)*
= 32 - (32 - n)
= 32 - 32 + n
= n.

You can substitute any symbol ($, ;, etc.) for the * if it makes it easier to understand.

 

[der2002]

it's not exponent notation, it's function notation. Imagine if instead of the * symbol, they used the @ symbol. You can envision this question as a parenthesis within parenthesis. If n* just means (32-n), then (n*)* is (32-(32-n)

 

[Soyjoy]

Make sure you don't confuse GRE symbols (and their locations, i.e. star in place of exponent) with actual mathematical symbols. You have to ignore those impulses because that's how they might confuse you..

 

[Armymutt25A]

Yes, it confused me. A variable is a variable to me - the style of it matters not. Thanks.

 

[HopefulAg]

Oh man I would've totally missed that one. The placement of the asterisk makes it look like an exponent, not a placeholder. That's not really a fair question IMO.

 

[Armymutt25A]

Yeah, whatever happened to f(x)?