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Help with integral calculus!

од SciBerC, 07. август 2014.

Поруке: 4

Језик: English

SciBerC (Погледати профил) 07. август 2014. 00.37.54

For my math class I need to solve a series of equations (all of which deal with antidifferentiation), now I understand the simple stuff such as: ∫2x dx=2x^2/2=>∫2x=x^2, and I also understand how to solve derivatives with the form ∫(ax+b)^r dx=((ax+b)^(r+1))/(a*(r+1)), however, when I have to solve derivatives with the special case rule, I get a little confused: rule ∫(ax+b)^-1 dx=1/a*ln(|ax+b|)+c, where ln is a natural logarithm, ln=loge..

Well anyway, I can solve them when the equation is straight forward, however,my teacher did not go over dealing with derivatives of the form ((ax+b)^2)/x... How do integrate this form of a derivative? the same also applies for the form x/(ax+b)^2, can someone please help me with this? Also, if you know any math terms in esperanto could you also chuck them in? Like I think 1+1=2 is something like unu plus unu estas du or unu plus unu egalas du..

Anyways thanks in advance! ridego.gif Dankon por via helpo! ridulo.gif

CALVO (Погледати профил) 07. август 2014. 03.36.40

Saluton!
(1)
∫(((ax+b)^2)/x)dx = ∫((ax)^2 + 2abx + b^2)/x dx
= ∫a^2*x dx + ∫2ab dx + ∫b^2/x dx
= (ax)^2/2 + 2abx + b^2*ln(x) + konstanto //

(2)
∫x/(ax+b)^2 dx .
{Do you know how to work with the substitution? Basicly you just choose which part you can change for u (in this case it`s ax+b)and then derivate it to get du (in this case the derivate of ax+b is a)}
Anstataŭo: [u = ax+b => du = adx, dx = du/a, x= (u-b)/a]
=> ∫x/(ax+b)^2 dx = ∫((u-b)/a)/u^2 *du/a
= ∫(u-b)/(au)^2 du = ∫1/(a^2*u) du - ∫b/(au)^2 du
= ln(u)/a^2 + (b*1/u)/a^2 + K1
anstataŭo: u = ax+b
= ( ln(ax+b) + b/*(ax+b) )/a^2 + konstanto //

Vi povas viziti http://www.wolframalpha.com/ por klarigi viajn demandojn.

SciBerC (Погледати профил) 07. август 2014. 06.18.57

Dankon por via helpo!! ridulo.gif

kaŝperanto (Погледати профил) 07. август 2014. 14.27.30

Substitution comes in very handy, so learn it well.

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