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In step 3, you have multiplied 1. & 2. What would be the answer if you divide 1. by 2. ? I am kinda confused. I get f(5x)/f(x/5) = 1/5^6. Help, thanks!

In step 3, you have multiplied 1. & 2. What would be the answer if you divide 1. by 2. ? I am kinda confused. I get f(5x)/f(x/5) = 1/5^6. Help, thanks!

The questions is "what is the value of \(f(5x)*f(\frac{x}{5})\)..." (f(5x) multiplied by f(x/5)) not "what is the value of \(\frac{f(5x)}{f(\frac{x}{5})}\)..." (f(5x) divided by f(x/5)).
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Re: If f(x)=125/x^3, what is the value of f(5x)*f(x/5) in terms [#permalink]

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18 Jul 2013, 21:47

Bunuel wrote:

mneeti wrote:

The questions is "what is the value of \(f(5x)*f(\frac{x}{5})\)..." (f(5x) multiplied by f(x/5)) not "what is the value of \(\frac{f(5x)}{f(\frac{x}{5})}\)..." (f(5x) divided by f(x/5)).

Please refer your Ist response in this topic, the quoted part asks to find \(\frac{f(5x)}{f(\frac{x}{5})}\). Also, the question I have from my source of practice questions requires to find the \(\frac{f(5x)}{f(\frac{x}{5})}\). Thanks!

The questions is "what is the value of \(f(5x)*f(\frac{x}{5})\)..." (f(5x) multiplied by f(x/5)) not "what is the value of \(\frac{f(5x)}{f(\frac{x}{5})}\)..." (f(5x) divided by f(x/5)).

Please refer your Ist response in this topic, the quoted part asks to find \(\frac{f(5x)}{f(\frac{x}{5})}\). Also, the question I have from my source of practice questions requires to find the \(\frac{f(5x)}{f(\frac{x}{5})}\). Thanks!

Please refer to the same post: in order the answer to be A, the question should read: If \(f(x) = \frac{125}{x^{3}}\), what is the value of \(f(5x)*f(\frac{x}{5})\) in terms of f(x)? _________________

\({f(5x)}*{f(\frac{x}{5})}={f(5)}*{f(\frac{1}{5})}=125^2\) and since \(f(x) = f(1)=125\), then \({f(5x)}*{f(\frac{x}{5})}=125^2=(f(x))^2\).

Answer: A.

Hope it's clear.

Can we take constant 5 outside of f(5x) i.e 5f(x) ? I was able to arrive at the answer by taking constant outside of the function,but not sure whether it is correct approach or not.

\({f(5x)}*{f(\frac{x}{5})}={f(5)}*{f(\frac{1}{5})}=125^2\) and since \(f(x) = f(1)=125\), then \({f(5x)}*{f(\frac{x}{5})}=125^2=(f(x))^2\).

Answer: A.

Hope it's clear.

Can we take constant 5 outside of f(5x) i.e 5f(x) ? I was able to arrive at the answer by taking constant outside of the function,but not sure whether it is correct approach or not.

It depends on HOW are you doing that. Please show your work.
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Re: If f(x)=125/x^3, what is the value of f(5x)*f(x/5) in terms [#permalink]

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30 Aug 2014, 07:13

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Re: If f(x)=125/x^3, what is the value of f(5x)*f(x/5) in terms [#permalink]

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24 Jan 2017, 06:22

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
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Re: If f(x)=125/x^3, what is the value of f(5x)*f(x/5) in terms [#permalink]

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18 Jul 2017, 18:29

This can be solved like this. It is important to understand the difference between (a) and (b) for instance (F(x))^2 means you square the whole function while F(x^2) means you plug in X^2 everytime you see X. A good video explaining how function notation works is here. It's not my video but he explains it well if you missed this step.