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Integral Calculus ( integrate by u-substitution) Note: S = integrate symbol S (x- 1/x)^2 dx?

I would like to know when to use u-substitution and of this is applicable 

I would like to know some rules in using u-substitution this would really help me 
Anyway this is needed for today thanks for your help!!!




Sagot :

Usually, u sub is used when you find a suitable u such that it is easy to differentiate and its derivatives will be seen as factors of f. In this problem, using u sub would only make it more complicated.

If we expand it, we'll get

∫ [tex] \frac{ x^2-2x+1}{ x^2 } [/tex] dx

= ∫ [tex] \frac{ x^2 }{  x^2 } [/tex] dx - ∫ [tex] \frac{-2x}{  x^2  } [/tex] dx + ∫ 1/x² dx

= ∫ dx + 2∫ 1/x dx + ∫1/x² dx

= x +2lnx -1/x