Another maths problem thread

[ríomhaire]

I should know how to do this, but my mind is drawing a blank. Integration by parts isn't working and I can't figure it out.

Integrate:
(x + 5) / (x^2 + 5)

 

[Dan]

http://integrals.wolfram.com/index.jsp

Good luck doing that by hand.

 

[Teta_Bonita]

Make the trig substitution x = Sqrt(5)*Tan(theta).

 

[Avoidist]

How to get the wolfram solution:

Split numerator in two giving
x / (x^2 + 5) ............(1)
and
5 / (x^2 + 5) ............(2)

Solve (1) by first seeing that
d/dx [ln(x^2 + 5)] = 2x / (x^2 + 5) - this is just the chain rule, i.e. let u=x^2 + 5, then dy/dx = (dy/du)(du/dx)

Solve (2) by the x=sqrt(5)tan(?) substitution thing.

 

[15357]

I hate integrattion. Probably the reason why I chose to do Maths I but not Maths II and above.

 

[Dog--]

Why you guys call it maths? Isn't it math?

 

[Vigilante]

Why you guys call it maths? Isn't it math?

It's all about the maths in the UK and Australia.

 

[Xendance]

Why you guys call it maths? Isn't it math?

Math sounds retarded if you come from the UK.

 

[Qonfused]

Why you guys call it maths? Isn't it math?

Mathematics

I guess it makes sense, but to us HERK A DERP AMIRIKANNS, maths sounds odd.

 

[Dog--]

Well I read that book - Curious incident of the dog in the night-time - and he aways says maths (story takes place in UK), but I assumed it's because of his aspergers..

 

[ríomhaire]

We say maths, because it is short for a plural world: Mathmatics.

 

[Dog--]

EDIT: Wait nvm that didn't make any sense.

 

[Mellish]

It's our mandatory "make you feel stupid" thread.