Update cheatsheet.fr.md

12.temporary_ins/32.sets-systems/30.n3/20.systems/20.overview/cheatsheet.fr.md

@@ -79,17 +79,18 @@ RÉSUMÉ<br>
   $`\displaystyle\begin{align}
    \;\;&\Longrightarrow\quad\left.\dfrac{dN}{N}\right\lvert_{\,\bigt}=r\,dt\\
    \\
-   &\Longrightarrow\;\int_{N(t_1)}^{N(t_2)}\dfrac{dN}{N}=\int_{t_1}^{t_2} r\,dt\\
+   &\Longrightarrow\;\underbrace{\int_{N(t_1)}^{N(t_2)}\dfrac{dN}{N}}_{\begin{array}{c}
+   \Primitive \big(\dfrac{dx}{x}\big)\\ =\;ln\,|\,x\,|}=\int_{t_1}^{t_2} r\,dt\\
    \\
    &\Longrightarrow\;\big[\,ln\,|N|\,\big]_{N(t_1)}^{N(t_2)}= r \,\big[\,t\,\big]_{t_1}^{t_2}\\
    \\
    &\Longrightarrow\;\underbrace{ln\,|N(t_2)|-\,ln\,|N(t_1)|}_{\color{blue}{
-   N>0 \;\Longrightarrow\;|N|\,=\,N}} = r\,(t_2 - t_1)\\
+   N\,>\,0 \;\Longrightarrow\;|N|\,=\,N}} = r\,(t_2 - t_1)\\
    \\
    &\Longrightarrow\; ln\,N(t_2) = ln\,N(t_1) + r\,(t_2 - t_1)\\
    \\
-   &\Longrightarrow\; \underbrace{exp\big[ln\,N(t_2)\big]}_{\color{blue}{exp(ln\,x)\;=\;x}}
-   =\underbrace{exp\big[ln\,N(t_1) + r\,(t_2 - t_1)\big]}_{\color{blue}{exp (a+b)\;=\;exp\,a\;\times\; exp\,b}}\\
+   &\Longrightarrow\; \underbrace{exp\big[ln\,N(t_2)\big]}_{\color{blue}{exp\,(ln\,x)\;=\;x}}
+   =\underbrace{exp\big[ln\,N(t_1) + r\,(t_2 - t_1)\big]}_{\color{blue}{exp\,(a+b)\;=\;exp\,a\;\times\; exp\,b}}\\
    \\
    &\Longrightarrow\; N(t_2)=N(t_1)\,exp\,\big[r\,(t_2 - t_1)\big]\\
    \\