Homework help (I need to UNDERSTAND this..)

[mooeypoo]

Guys,

 

I have some homework and the answer itself matters less - I just can't figure out *how* to do these type of questions.. I figure it has to do with an elaborate chain rule, but.. I can't do it right. I would appreciate help in this.

 

btw, sorry if this is in the wrong forum - I couldn't find the goold ol' "Homework Help" forum.

 

The question is this:

 

f(x) = 2^[3^(x^2)]

 

find dy/dx.

 

Again, I *have* a final answer, I just don't understand how to do the chain rule itself on this one.. it seems like a double chain rule? ergh. Anyone has some sort of method/trick for these type of questions?

 

Thanks!

 

~moo

[w=f[z]]

Do a series of substitutions. For example;

let [math]f=2^t , \ t=3^{x^2}[/math]

[math]\Rightarrow \frac{df}{dt}=2^t \ln{2}[/math]

So [math]2^{3^{x^2}} \ln{2} [/math] will be in your answer.

 

Then let [math]x^2=s[/math] and differentiate [math]3^s \Rightarrow 3^s\ln{3} \Rightarrow 3^{x^2} \ln{3} [/math], so that too will be in your answer via the chain rule and so on. See the pattern?

 

Good luck chap,

w=f[z]

[mooeypoo]

That sux.

 

 

Thanks though.. hehe.. I'll have to REALLY practice on that one, the multiple chainrule thing is confusing. I see the point now.. but.. er. I need practice, I think.

 

Thanks

 

~moo

[Country Boy]

That sux.

 

 

Thanks though.. hehe.. I'll have to REALLY practice on that one, the multiple chainrule thing is confusing. I see the point now.. but.. er. I need practice, I think.

 

Thanks

 

~moo

 

So basically, then it is your ATTITUDE that is the problem rather than the chain rule.

[the tree]

So basically, then it is your ATTITUDE that is the problem rather than the chain rule.

What precisely is wrong with Moo's attitude. Trying, asking for help and being aware of when he needs more practice seems a pretty good attitude to me.

[mooeypoo]

What precisely is wrong with Moo's attitude. Trying, asking for help and being aware of when he needs more practice seems a pretty good attitude to me.

 

"She."

 

But yeah, I didn't think there was nothing wrong with my attitude, this is a request for help, not an life-or-death argument. I just figured if someone's that critical of those who ask for help, he doesn't deserve responses back.

 

Plus, w=f[z] was so helpful, I didn't want to degrade the thread. Thanks to all that helped, I finished the course with an A-, which, considering the fact I am a full time employee, it's not too bad at all.

 

Cheers,

 

~moo

[Country Boy]

"That sux"

[mooeypoo]

Yeah, humor... The rest of what I said showed that I meant it as a "oh my oh my how complicated, how annoying that I need to sit on my tushy and study".

 

I'll try to avoid it next time.

 

In any case, Really, we're taking things way out of proportion.

 

I didn't mean it literally sux, and in case my assumption that you didn't mean to offend anyone is true, let's just drop the entire subject. Seriously. Let's practice math, instead, it's a lot more productive.

 

~moo

[Fuzzwood]

So in final you'll get

 

[math]

2^{3^{x^2}} \ln{2} * 3^{x^2} \ln{3} * 2x

[/math]

 

right? I always sucked at these things, but i want to know if i can finally do it too

[joshua.cook]

f'=2(^3(^(x^2)))ln2*3(^(x^2))ln3*2x

[Phi for All]

What precisely is wrong with Moo's attitude. Trying, asking for help and being aware of when he needs more practice seems a pretty good attitude to me.

I'm just going to be proactive here and praise the tree for his support. I want you to know how much the Staff appreciates positive feedback. It's too easy to go out of our ways to criticize.

 

Thanks, the tree, you've earned yourself some reputation there.

 

And mooeypoo, you just keep asking the questions darlin. It's great to have you here in the US away from all the tension. I hope your family is well.