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# Functions??

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Intern
Joined: 17 Jul 2003
Posts: 7

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18 Jul 2003, 10:53
Well, I am beginning to prepare for my GMATs and I have elected to brush up on my pathetic quanitative skills. I am working with "the official guide 10th edition" currently and have actually revived some long lost algebra skills, which i fear...Anyways, I was unable to revive the "functions" portion of my brain and I was hoping someone could point me in the direction of an online course specifically for functions. Math in general is very painful for me, so please find me something i'll be able to follow along easily.

I guess another question to ask is if functions are a major part of the quantitative section. Any thoughts?

Also, I suppose i'm in the same boat with "probabilities". Any info or help with either would be much appreciated.

Thanks.
GMAT Instructor
Joined: 07 Jul 2003
Posts: 607
Location: New York NY 10024
Schools: Haas, MFE; Anderson, MBA; USC, MSEE

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18 Jul 2003, 11:36
There is no need to study functions, per se. There is, however, a category of strange problems called "defined functions". Typically, ETS will define a function using a strange symbol.

For example:

Suppose x##y = (x + y)/y. What is (4##5)##2?

The trick is to simply follow directions carefully and make sure you add the appropriate assumed parentheses.

The more difficult type of these problem are like this:

Suppose x##y = (x + y)/y. Is the ## operation associative? (i.e., is (a##b)##c = a##(b##c)?

Be careful. Sometimes they use the same variables in the implementation as the ones that they use in the definition of the problem. Remember, the variables in the DEFINITION of the functions are merely placeholders. To avoid confusion, simple change the variables in either the definition or the implementation of the defined function so that they are mutually unique.

Hope this helps.
Intern
Joined: 17 Jul 2003
Posts: 7

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18 Jul 2003, 11:59
I appreciate the insight, but i have to say that i am not quite clear on your examples. It probably very easy, but I don't quite see the process. Can you elaborate a bit?
GMAT Instructor
Joined: 07 Jul 2003
Posts: 607
Location: New York NY 10024
Schools: Haas, MFE; Anderson, MBA; USC, MSEE

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18 Jul 2003, 12:07
The test makes up phoney functions using arbitrary symbols, then asks you to evaluate them using real parameters. All you need to do to get these types of problems right is to carefully apply the "functions" EXACTLY as they define them.

Is this more clear?
Intern
Joined: 17 Jul 2003
Posts: 7

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18 Jul 2003, 12:14
Yes. That is clear, but i am more of a visual learner. If it's not too much trouble can you write up a real problem that i can visually follow? If this is too much trouble, then dont worry about it. I don't want to be a burden and appreciate your input.
GMAT Instructor
Joined: 07 Jul 2003
Posts: 607
Location: New York NY 10024
Schools: Haas, MFE; Anderson, MBA; USC, MSEE

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18 Jul 2003, 12:17
Let A@B = A + 2B. What is 4@(1@3)?

By the definition above, 1@3 = 1 + 2*3 = 7, and 4@7 = 4 + 2*7 = 18.

Hence, the answer is 18.

Pretty basic, huh?
Intern
Joined: 17 Jul 2003
Posts: 7

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18 Jul 2003, 12:44
thanks you,

I appreciate your help...
18 Jul 2003, 12:44
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# Functions??

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