144144 wrote:

for all integers N, the function F is defined by f(n)=a^n

where a is a constant. what is the value of f(1)

1. f(2)=100

2. f(3)=-1000

F(2)=10^2=a^2

so a=10/-10 BUT

it can also mean that a=1/10 and n=-2

More importantly, there is a mathematical mistake in what you are doing. If

f(n) = a^n

then when we evaluate f(2), we replace n with 2 on the right side of the equation above:

f(2) = a^2

If instead we replace n with -2 to get a^(-2), as you have done, then we are finding the value of something completely different - we're finding the value of f(-2). The value of f(-2) is not relevant in this question since we aren't given any information about it.

I've gone through the entirety of the Quant material in OG-12 looking for errors or typos. There are a few in the solutions section (some typos, but also some mathematical or logical errors), and there are a couple of minor errors in the explanatory material at the beginning of the book. As best I can tell, the questions themselves are free of mistakes in OG-12 (though the first printing of OG-11 had a couple of misprints in the questions section). On the whole it's a very well-edited book, at least relative to most GMAT publications.

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