Partial Derivatives

One of you FE takers has a very clear, concise, easy to follow cheat sheet or video on how to do these ... please help.

f(x) = 2x1x2 + 2x2 - x12 - 2x12

Need to differentiate for both variables, and this is on the tip of my brain, but I'm not getting it, especially with these guys 2x1x2

Thanks

I'm not able to directly answer your question, but if you need extra help with calculus, I found the following two resources very helpful when I was studying for the FE:

http://ppi2pass.com/calculus-refresher-for-the-fe-exam-calfe.html

https://www.khanacademy.org/

Thanks, I don't even necessarily need to know how to do this. I just need the correct solutions when they come up.

Does anyone use Maple?

:facepalm:

I answered your original question and didn't see your name and didn't recognize your avatar. I thought you were studying for the FE.

LOL .... nope .... never again. But I am a glutton for punishment. Taking a few classes

f(x) = 2x1x2 + 2x2 - x12 - 2x12

Partial in respect to x1 = 2x2 - 2x1

Partial in respect to x2 = 2x1 + 2

Is that right? Basically whatever variable you're taking a derivative of you treat the other variable(s) as a constant.

Used Maple a few times a long, long time ago.

Should be...

Partial in respect to x1 = 2x2 - 2x1 - 4x1

W9TWJ said:

Should be...

f(x) = 2x1x2 + 2x2 - x12 - 2x12

Partial in respect to x1 = 2x2 - 2x1 - 4x1

Partial in respect to x2 = 2x1 + 2

Click to expand...

This.  JQP, always ask an electrical when dealing with PFE.  We can usually do that in our sleep. :thumbs:

f(x) = 2x1x2 + 2x2 - x12 - 2x22

ok I'm an idiot and typed that last part wrong, should've been -2x2 2

In respect to X1 that just goes away, right?

In respect to X2 become -4x2

John QPE said:

f(x) = 2x1x2 + 2x2 - x12 - 2x22

ok I'm an idiot and typed that last part wrong, should've been -2x2 2

In respect to X1 that just goes away, right?

In respect to X2 become -4x2

Click to expand...

Correct!  Now get back to work and quit messing around with FE practice problems! ldman:

Oh, this is only the beginning my friend

Ooh, let's do Fourier and/or Laplace transforms next!

knight1fox3 said:

Ooh, let's do Fourier and/or Laplace transforms next! [emoji3]

Click to expand...

You should be banned for that.

knight1fox3 said:

Ooh, let's do Fourier and/or Laplace transforms next!

Click to expand...

I'm out...

knight1fox3 said:

Ooh, let's do Fourier and/or Laplace transforms next!

Click to expand...

Did them last night!!

I also bought Maple last night V:

http://calculus-calculator.com/integral/

https://www.symbolab.com/solver/calculus-calculator