Addition et soustractions des fractions algébriques: Dénominateur commun, puis + ou - numérateurs !

Got it !

$\LARGE \frac{a}{b} - 2\frac{a}{3b} $ $\LARGE \frac{3a}{3b} - \frac{2a}{3b} = \frac{3a-2a}{3b} = \frac{a}{3b} $
$\LARGE \frac{a}{x^2b} + \frac{a}{xb^3} $ $\LARGE \frac{ab^2}{x^2b^3} + \frac{ax}{x^2b^3} = \frac{ab^2+ax}{x^2b^3}$
$\LARGE \frac{a}{b} - \frac{b}{(a} =$ $\LARGE \frac{a^2}{ab}$ - $\LARGE \frac{b^2}{ab}$ = $\LARGE \frac{a^2 - b^2}{ab}$
$\LARGE \frac{2}{x^2 - x} + \frac{1}{x} =$ $\LARGE \frac{2}{x(x - 1)}$ + $\LARGE \frac{x - 1}{x(x - 1)}$ = $\LARGE \frac{1 + x}{x(x - 1)}$
$\LARGE \frac{a-b}{a^2+ab} - \frac{1}{(a+b)^2} =$ $\LARGE \frac{}{}$ $\LARGE \frac{}{}$$\LARGE \frac{a^2-b^2 - a}{a(a+b)^2}$