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ok differentiate y = lnx..... y'=1/x Hmmm, not quite yr 11 stuff :P hmm by parts I get int lnx = xlnx - x but when I use the integrator (http://integrals.wolfram.com) I only get that it = xlnx.... What did I do wrong there? edit: woah, I'm definatly doing something wrong because...

course not, I'm sure we could find other ways to satisfy each other...

I normaly forget them so I just derive it :)

Thanks Constip8edSkunk I see where I made my error now, it was very stupid too, *sigh* always the way...

yeah, that's fine for the top of the fraction but you also have cos² on the bottom. How did you get that?

I think you've made a mistake with your substitution in this line: =∫ 4cosθ/16cos²θ 4cosθ dθ I think you have let x=4cosθ insted of 4sinθ...

Ok, I've changed my mind all is not good... could you give me a hand with: int (sqrt(16-x^2)/x^2) dx Hint: let x=4sinθ I can get to: =-(1/16)cotθ but from there I've no idea

ahhh, so that's how it works :) thankyou very much all is good now :cool:

Thanks teoh. I just did the first one it actually ends up being: 1/2ln(x^2+1)-arctanx because you multiply the integrand by 2/2 With the second one that's what I did but I ended up with a mess so could somebody actually do the working for me? ( I assumed you meant 4/(x-1)^2 - 2 btw...

Hey, we've just started integration and I'm struggling a bit with some of the questions, could someone show me how to do: 1. int ((x-1)/x^2+1))dx 2. int ((4/(x^2-2x-1))dx Thanks heaps :D

conq chemistry has a good run down of it

Ignorant, not arrogant. If I was arrogant I would think I'm better at 4u than all you guys, trust me I hold no such illusions :p

Ahh ok I get it now, with my half flight projectile motion the only vertical displacement is down so if I take down as being negative then delta y is also negative. Cheers everyone :)

Hey, could someone verify this for me? If you are looking at half flight projectile motion (eg a ball rolls off a table) you take g to be positive. i.e deltay=u_yt + 1/2 a_yt² ------------- From the formula sheet Becomes: deltay=1/2 gt² as...

about 25, I'm surprised with some of these numbers, I thought my school had a lot!

with the person in the lift, they are in an inertial frame of reference if they have reached terminal velocity because at this point they are not accelerating. Sure they have the earth accelerating them towards the centre but they also have friction applying an equal and opposite force. Hence...

You make the 'x's negative because that is the definition of odd and even functions. for example: f(x)=x^2 therefore f(-x)=(-x)^2 now a negative by a negative gives a positive therefore: f(-x) = x^2 =f(x) therefore f(x) is even or g(x)=x^3 g(-x)=(-x)^3 now 3 negatives give a...

I crash, that's my main problem actually. I get the question out, takes about three pages. Then tell my teacher there must be an easier way and he then does it in about half a page, very frustrating! But I normally manage to finish my tests so it's all good.

It won't help that's for sure. Personally I found conics the hardest topic we covered in 4u so far, but then again we have only done graphing complex no. and conics :P. Just make sure you pay attention, the parametrics for the ellipse and hyperbola are different from those involved in the...

Our class is really good actually. Because it's a selective high school we have 12 people in our class and we are in the same class for everything. (well all maths anyway) So the teaching style is pretty much the same throughought, although I will admit the lectures of the 4u stuff do tend to...