# Math Help - function question

1. ## function question

Let the function f be defined by f(x) = x+1.
If 2f(p)=20, what is the value of f(3p)?

2. ## Re: function question

Originally Posted by klg
Let the function f be defined by f(x) = x+1.
If 2f(p)=20, what is the value of f(3p)?
Come on. You do some work.
You know that $2(p+1)=20.$

3. ## Re: function question

Plato,
I am a parent helping her son with his SAT review.
I have spent HOURS doing math problems and figured all of them out except this one.
DON'T tell me to do some work.

4. ## Re: function question

Originally Posted by klg
Plato,
DON'T tell me to do some work.
Frankly I will tell you anything I want because you came off as demanding that we work a problem for you. You could have easily explained your position and your son's problem. But you chose not to explain but demand. We are neither a homework service nor a tutorial service. You did not even atop to consider the help I did give you freely.

Solve $2(p+1)=20$ then find $f(3p)$.

Let me be blunt with you. If your son cannot do that, then you are wasting money on the SAT.
I am retired chairman of a university mathematics department so I should know.

5. ## Re: function question

2(p+1) = 20 => 2p = 18 => p = 9. Plugging into f(3p) = f(27) = 28. To avoid an interaction like above, write out any reasoning (verbal or in symbols).

6. ## Re: function question

Tell what you want.
I have always replied in a thankful affirmative to any help I have received. (only 3 questions total I believe)
As a math department chairman, you should be aware that sometimes people spend so much time working the difficult problems the obvious gets by them.
My son is an exceptional student. I am glad you are retired so there is no chance he will end up with you as a professor.
You have chosen a poor name to represent yourself with.
Your counterparts on the forum have been very nice.
Perhaps you should learn from them.

7. ## Re: function question

Thank you very much for the explanation!