(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Let f(x) = axe^((bx)^2). Find the value for a times b if it's known that there's a max value of 2 at x = 3.

Second, There is one line which is tangent to the curve y = 1/x, at some point A and at the same time tangent to the curve x^2 at some point B. What is the distance between

A and B?

2. Relevant equations

For the first I realize that I have f'(3) = 0 and (I think) f(3) = 2.

Second, I think I can set the derivatives equal to each other and solve for x.

3. The attempt at a solution

I can then use these equations to solve for a and b, however I guess this is more an algebra problem because I seem unable to do so. I also need verification that that second equation makes sense. If it does, I think I'll be more able to do this question because I can solve for b in a way I couldn't with the first equation (if I took ln of both sides ln0 would be undefined and it wouldn't make sense, I think).

Second, when I tried to solve for x I ended up with x = 1/2 which lead me to a solution eventually, by the distance formula, of 9/16 + 1/16 which is not correct based on the test answers.

Any help would be appreciated here, thanks guys!

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Some Derivatives Questions

**Physics Forums | Science Articles, Homework Help, Discussion**