Integral of 1/sqrt(polynomial) -- Outside the box thinking

[hq319]

did you forget the 1 over root 2 ? lol

[kanopopo]

im scared of collage now

[markov2b1]

very clever. great video!!! 

[goamira]

how do you solve the integral 1/(sqrt(25-x^2))dx

[markov2b1]

@goamira

first factor out the 25 from the inside the square root. this gives you 1/5 * integral ( 1 / sqrt (1- (x/5)^2)) , now u = x/5

so 5du = dx, so the 1/5 and 5 cancel. you are left with integral 1 / sqrt ( 1 - u^2) = arcsin u + c , or arcsin x/5 + c

[ImmanualKant1989]

Kool thank you!

[ksonggg]

why can't the end just be ln of the entire bottom times its derivative? since it's one over the denominator.

[ElliotTM92]

@ksonggg Because that's not the actual rule. You're thinking of just ln(x).

But the derivative of ln[f(x)] = f'(x)/f(x). e.g. f(x) = x^2

ln(x^2) => 2x/x^2 and so on.

[tamaratm22]

:D :D :D thanks!!!!!!

[sheazer]

his answer is wrong. in the second integration U must be 2X not X. check wolfram (the online integral solver, just google it) and the answer is different.

[lcunha85]

Thanks. This was very helpful.

Keep making these videos, please.

Coundn't you do something on series and sequences, please?

[gamesguru]

You forgot two things:

The 1/rt(2) on the numerator in the second half of the video and the du/rt(u) du.

Other than that, I found this video VERY useful and it's an excellent example.

[bkjoelover]

lol tome is cute cuz he got jokes. holler back at your man bro.

[259]

Ugh... damn integral calculus.

[tingcong222]

the one over root 2 doesnt really matter...it's just a constant and can be carried out of the integral (put it in front)

[newazninvasion]

you missed the 'one over square root of 2' in line three (check video @ time 7:25)

[jonathancolucci]

nasty problem

[newazninvasion]

you missed the 'one over square root of 2' in line three (check video @ time 7:25)

[bkjoelover]

butt nasty alrite

[19madrid42]

some good stuff, all be it abit rushed towards the end.

hence the mistake of omitting the sqrt of 2 & also talking about u to the power of 3/2 instead of 1/2 in the 1st integrand.

i'd also like to see them confirm the integral by differentiation. they may then show us some differentiation tricks.

[bkjoelover]

tom is a bad boy

[hecatonchiress]

this one was kind of difficult with all these things in the last ppart..i got mixed up when i tried it =( nice job anyway this guy explains very very well

[chrisrave]

Very nice, thanks.