# Search results

1. ### Integration by trig. substitution

Hello everyone I have an exam tomorrow and I would really appreciate if someone could tell me what I did wrong with this exercice. I did it on paper and I scanned it. Here is the link to the scan: The answer in the book is sqrt(x^2 + x +5/4) + 2ln(sqrt(x^2 + 2x + 2) + x +1) + C...
2. ### Is my book wrong?

I have this integration problem that I did but it doesnt give me the right answer. But there are like 3 other similar exercices I did the same way and I got all the right answers.. maybe it is my book (I dont think so ... :p) It's an integration problem: \int tg^3(4x) sec^4(4x)dx heres...
3. ### Integration problems

Hello everyone. I have been trying to do those 2 exercices for a while now and I can't get it.. We just started doing Integration by parts (is that how you call it in english?) here are the problems 1) \int{ (x^3)(e^{x^2})} and 2) \int{ \frac{{(x)(e^x)}} { (x+1)^2}} for the 2nd...
4. ### Limit problem

Hello, I have two questions concerning limits 1) lim x-> 0+ x^(sinx) 2) lim x-> +inf. (9^x)/(8^x) The first one gives me 1 (e^0 = 1) .. is that correct? The 2nd one I dont know how to do. Can someone please explain the 2nd one for me? Thanks a lot
5. ### Limit question (inf. - inf.)

EDITED THE EQUATION Hello all, I have this problem I can't solve.. it is a infinite - infinite. I tried it around 5 times and can't find the correct answer (infinite). I'm pretty sure I have to put in evidence x^2 and use a limit law but I can't find the answer.. can someone help me for...
6. ### Can I do this? (integral)

Hello all, and sorry for making all those threads :shy: I just want to know if I can do this (especially the last part) \int{} \frac{-k\ \lambda \ dx \ x \vec{i} + 2\ k\ \lambda \dx \ \vec{j}}{(x^2 +4)^{3/2}} = \int{} \frac{-k\lambda (x \vec{i} - 2\vec{j}) \ dx}{(x^2 +4)^{3/2}}...
7. ### Can you integrate a vector?

Hello, I just wanted to know if you can integrate a vector, and if so, how. Here is a problem: A charged piece of metal of linear density 2 * 10^-6 * x , between x=2 and x=5. I found its charge by integrating.. and it is 21 micro C. Now that's what I want to know: calculate the electric...
8. ### Coulomb's law vector question.

Hello, I have a simple exercice I'm having trouble to solve. So we have a) and b) a) asked the force applied on a charge.... and the answer was \vec{F_{res}.}= Qkq ( -0,222 \vec{i} -0,250\vec{j}) N that's not a problem here.. that was the good answer. Now in b), they're asking where...
9. ### Simple limit questions help (work is there)

Hello, I have those limit question to answer. (I applied Hospital Law) 1) lim cotgx / lnx x-> 0+ Heres what I did: 1) form infinite/infinite; -(cosec x)^2 / (1/x) = -2cosecx*-cosecx*cotgx / (-1x^-2) = -2(cosecx)^2 *cotgx * x^2 = 0 (wrong answer, I dont understand what's wrong...
10. ### Electricity and magnetism

Hello, I was wondering if you guys know any websites/ free books/ any other ressource about physics electricity and magnetism, since this is my next class and I want to try to read about it before starting. I have download an e-book from the sticky, but I'd like other sources. feel free to...
11. ### Simple limit question

Hello, I tried doing this limit problem: lim (sinx)/x^3 x-->0 here's what I did: (lim sinx)/(lim x^3) which should give something like 0,000000000...1 / 0,00000000001 since lim sinx (x->0) = 0 and lim x^3 = 0 too. When I make the graphic in maple, the answer is +infintiy, and...
12. ### Started talking about integrals

Hello everyone We just started talking about integrals. Unfortunately, our teacher wasn't there last class so we just had to figure it out by ourselves.. and integrals are going to be about 50% of our final exam.. so I was wondering if someone knows some websites to help me learn integrals...
13. ### Graphical link between function and derivate

Hello all, first, excuse my english I dont speak it very well I have a problem. We have two sheets. One are graphics of functions, and the other are graphics of the derivate of those function. Now my problem is I dont know how link a graphic of a function to the graphic of its derivate. I...
14. ### Non-uniform circular motion

Hello all, I need help to understand non-uniform circular motion. I know there's a centripetal acceleration and a tangential acceleration and the result of both are the acceleration. But what I dont understand is how can I find the tangential acceleration. I've been searching for a while now...
15. ### Detailed problem I did need verification

Hello all, I need to find the acceleration of this system. I did all the calculations but I'm stuck at the end and I'm pretty sure I did something wrong.. Could someone verify this? I just scanned the paper I'm working on. Also, sorry if I dont use the same signs you use, I'm translating this...
16. ### Urgent help need on easy significant number question

Hello guys. I have a little problem here.. we are doing a colorimeter (sorry in advance for the english errors. I dont know if it is called like that in english im translating from french.) experience and I have to use this formula D = e* L * C e= D/ LC where L is a constant 1cm. L= 1...
17. ### Need to determine an angle depending on acceleration

Hi guys. We did an experience on an inclined plan and I got this acceleration: -0,324 m/s2 . Now all I know is this: the mass of the object was 552g. g = -9,8 m/s2 and I need to find out what was the angle of the plane. I have to give this tomorrow so I need help on this please.. the teacher...
18. ### Need help for a projectile problem

Hello.. There is a projectile problem that I can't seem to resolve.. I have tried it for more than 30min now and can't find out how to do it.. I got an exam in 2 days so would someone please help me and tell me how to do this exercice: A basket-ball is launched at an angle of 45 degres (it...
19. ### Need help for a mechanic problem

Hi guys.. this is my first post. Sorry if I use terms that you don't use since I translate it from french.. I need help doing this problem. I tried it a few times but I can't find the answer. I tried to do the V(x) (speed or velocity I think) and find it from there but still can't manage to...