diff --git a/analyse/main.tex b/analyse/main.tex index a78f975..b4c8b0d 100644 --- a/analyse/main.tex +++ b/analyse/main.tex @@ -258,15 +258,19 @@ \paragraph{Exemple} \begin{align*} - \int_0^{\ln{\sqrt{3}}} \frac{1}{e^x + e^{-x}}\,\mathrm{d}x\text{,\quad on pose }u=e^x + \int_0^{\ln{\sqrt{3}}} \frac{1}{e^x + e^{-x}}\,\mathrm{d}x\text{,\quad on pose }u&=e^x \\ + u' &= e^x = \frac{\mathrm{d}u}{\mathrm{d}x} \\ + \mathrm{d}x &= \frac{\mathrm{d}u}{e^x} = \frac{\mathrm{d}u}{u} \end{align*} + Cela nous donne~: + \begin{align*} - &= \int_{e^0}^{e^{\ln{\sqrt{3}}}} \frac{1}{u + \frac{1}{u}}\,\frac{\mathrm{d}u}{u} \\\\ - &= \int_1^{\sqrt{3}} \frac{1}{u^2 + 1}\,\mathrm{d}u - = [\arctan{u}]_1^{\sqrt{3}} - = \arctan{\sqrt{3}} - \arctan{1} - = \frac{\pi}{3} - \frac{\pi}{4} = \frac{\pi}{12} + \int_{e^0}^{e^{\ln{\sqrt{3}}}} \frac{1}{u + \frac{1}{u}}\,\frac{\mathrm{d}u}{u} \\ + &= \int_1^{\sqrt{3}} \frac{1}{u^2 + 1}\,\mathrm{d}u \\ + &= [\arctan{u}]_1^{\sqrt{3}} \\ + &= \arctan{\sqrt{3}} - \arctan{1} \\ + &= \frac{\pi}{3} - \frac{\pi}{4} = \frac{\pi}{12} \\ \end{align*} \clearpage