What is the Substitution Method for Integrating a Rational Function?

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Homework Statement



∫1/(x^2+2x+2) dx


Homework Equations





The Attempt at a Solution



u = x^2+2x+2
du = 2dx(x+1)

But I am left with an x and can not find the antiderviative
 
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Try the substitution u = x+1.
 
Using the substitution suggested by Pengwuino, you should get
\int \frac{du}{u^2 + 1}

Hopefully you know an antiderivative for this integral.
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...

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