Ok, I've got this problem, and I can get the answer except one part, I don't know how you get it.

The problem is...take the derivative of:
x^2 ln(1-x^2)

so i use the product rule....u' v +u v'

so i get:

2x ln(1-x^2) - ????/(1/(1-x^2)

for the ???? i am getting x^2, but the correct answer is 2x^3, i see that you can get 2x^3 by multiplying the 2x through the left side of the prob and get 2x * x^2, but why would you do that? or do you not do that? I'm confused! can anyone explain this? thanks!
greg

42... damn slacker.. :rolleyes:


























:flipoff2:

combine the product rule with the chain rule.

thanks!

you sure you got that written down right?

for the right half I get - (2x^3)/(1-x^2)

42

the answer is
2xLn(-(x^2-1))+(2x^3)/(x^2-1)

ok ... x^2 ln(1-x^2) dy/dx

chain rule ... 2x ln (1-x^2) + x^2 / (1/(1-x^2))

that is what you keep getting ... your forgetting dy/dx of (1-x^2) which is -2x. that goes on the upper portion of the fraction. x^2(-2x)=2x^3

yeah, i wasn't multiplying the dy/dx of the inside (1-x^2), i was just taking the dy/dx ,-2x and not multiply by the x^2
thanks!

Good old calc :D God bless the TI89, without it I would be screwed!! I still know as much as I would otherwise, I can just do it soooo much faster!

Got a test on infinite series and sums this friday :eek:

I don't see where you guy are getting your chain rule from. Theres no need for it.

Dervitative of Ln(Fx) = (1/Fx)dx or dx/Fx

Cahin rule would be something like Ln(Sin^2(x)) Where you would have DX of the LN part: 2Sin(x)/Sin^2(x) then the chain rule works on Dx of Sin = Cos(x)
so Dy/DX of Ln(Sin^2(x)) = (2Sin(x)/Sin^2(x)) * Cos(x)

Originally posted by SR5Dave

Got a test on infinite series and sums this friday :eek:

Just had one today on the same thing. It was pretty bad. And on our test you can use a calc but they never help.

I finished all my math, hell yea for the TI-89. Now I am taking a stastical analysis class, that shit is way harder than calc.

Vector calc is alot of fun.

i have a hungarian prof...way hard to understand, and the math book is not much help either. learning this on my own....i gotta take calc 2 next semester then i'm done with my math. i'm going for ME technology, if i decide to go with reg. ME, then i gotta take calc 3 and diff eq, but not sure which way i want to go with yet. teh technology side is geared more towards me, it's more hands on process type stuff. which is what i want to do with my business and career wise. thanks for the help!
greg

How are you getting those trig functions in there?

2nd semester calc (all integration here at CSUF) is a bitch of a class.

Originally posted by Weasel


Just had one today on the same thing. It was pretty bad. And on our test you can use a calc but they never help.
Thanks ass, I was thinking I'd do ok :flipoff2:


Yeah, 89's are tough to make em do sums!

just an example fo something that uses a chain rule from how I was shown to use it.

Originally posted by Toyoda
2nd semester calc (all integration here at CSUF) is a bitch of a class.

It was the second half of my 1st semes and the first half of my second... I found it to be pretty easy overall but LAME at times

Again; TI89=kickass even moreso for the big S

finished em all. the hardest class was mat 214 at cal poly pomona. it was the first multi-var teacher worked for JPL and all his stuff was application. take home test was 25 pages. it was hard and it sucked but i learned alot. i took 5 of 6 calcs with that guy. he was cool.

Actually the series stuff is pretty straight forward. Just keep you geometric, power series, kth test, rules all straight. I should have done decent on mine but I always have a horrible time taking tests.

And most of the other calc classes at our school you cannot use claculators for anything. this class you can but they don't see to help for the calc. I just use mine for additon, subtraction, ya know the hard stuff. :flipoff2:

we have a no calc rule this semester..none at all....i think it's easier that way, then you don't have to break it down more, and less room for error in the simple steps....

Originally posted by Weasel
Actually the series stuff is pretty straight forward. Just keep you geometric, power series, kth test, rules all straight. I should have done decent on mine but I always have a horrible time taking tests.

And most of the other calc classes at our school you cannot use claculators for anything. this class you can but they don't see to help for the calc. I just use mine for additon, subtraction, ya know the hard stuff. :flipoff2:
LOL, the best teacher I ever had was last semester, he was just EXCELLENT, one of the first things he said at the begining...

"All the lower math teachers say 'no calculators allowed, they hinder learning' well SCREW THAT, this little baby can do ANYTHING *pointing at TI89* *mocking other teacher: 'What do you do if it breaks? Huh????' ILL GET ANOTHER ONE!!!"

lmao

CALCULATORS??? You guys are pussies of the first order :rolleyes:

wait, you can't get this, but you want to bend tube for me. bwahaha. :flipoff2:

i don't think i'll ever use derivatives or logs bending tube!!!!:flipoff2:

Originally posted by Pazuzu
CALCULATORS??? You guys are pussies of the first order :rolleyes:

Damn, it warms my heart to hear this!

I still have a 20 inch K & E (hey, accurate to FOUR decimal places!!!). I TAUGHT slide rule in 8th grade.

Heh, heh, heh...

Originally posted by Pazuzu
CALCULATORS??? You guys are pussies of the first order :rolleyes:

Why? We still learn how to do it the same ways, and not every problem can be done with them. They are an extremely usefull tool.

Its like working on a truck with air tools. You're still using the same methods but fuckin A is it easier! And you could do it without them, but it just sucks. Its just a tool.

Originally posted by SR5Dave


Why? We still learn how to do it the same ways, and not every problem can be done with them. They are an extremely usefull tool.

Its like working on a truck with air tools. You're still using the same methods but fuckin A is it easier! And you could do it without them, but it just sucks. Its just a tool.
I don't have a problem with having them, and using them, but on tests??? Come on, the test is there to show a level of mastery of a subject, not to show who has more built-in equations saved on their handheld computer.

I use helpers when I'm doing equations in my research...about $500 of integral tables, log tables, etc. that I have collected over the years. But you still have to do the work yourself...

nah let em paz, that way i can get a job easier cause they have to use their calc to do the work and wont understand when they get the wrong answer