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[Bouchart]

Memorizing all of the formulas is supremely pointless IMHO.

I had a differential equations class like that once.

[Virex]

1) Most are simply not prepared for any "math" that goes much beyond rote memorization.

Heh, I'm nott prepared for anything that requires memorization.

Which is why I failed my last year :/

Over here some exams are what's called "open book exams", which means you can use your book (and sometimes all your notes as well) at the exam. Not that they are any easier then the normal exams...

[postal83]

Hrm... well I got a problem I spent a couple hours beating to death for CALC II and got nowhere.

Through u-substitution, find the integral of:
∫sqrt(7+e^t)dt

Any thoughts?

EDIT: forgot my dt (that's -1 point for me)

[Virex]

You're going to need a table of standard integrals for that. Tried u = 7 + e^t yet?

[Darvi]

integral sqrt(7+e^t) dt = 2 sqrt(e^t+7)-2 sqrt(7) tanh^(-1)(sqrt(e^t+7)/sqrt(7))+constant
Huh?

Try substituting e^t by U

[eerr]

Wrong substitution bro.

[Darvi]

It's what wolfram alpha gave me. Trying to figure it out now.

[eerr]

Ehh, Wolfram Alpha may be right.

It looks like e^t ends up on the bottom.

I don't think Calc 2 covers that.

[Virex]

Ehh, Wolfram Alpha may be right.

It looks like e^t ends up on the bottom.

I don't think Calc 2 covers that.

If it ends up there alone it's equivalent to multiplying with e^-t.

[Dr. D]

I think for that integral you have to do a trig substitution-ish thing where t=ln(tan(x)^2/7) and dt= the derivative of that * dx. You then should get something like the sec(x) * (a huge mess)dx,

Have fun!

[Darvi]

sec(x) is 1/cos(x), right?

[Dr. D]

Yes.

[eerr]

it can be converted with U=(7+e^t)
du=e^t dt

into an integral which is a pain in the ass

integral of sqrt(u)du/u-7
Doable with a certain trig substituition(thank god someone mentioned it above), which is beyond me at the moment.

[Darvi]

Yes.

Whooo! Go me!

[Dr. D]

I think the back substitution is a royal pain. The integral you get is not that hard.