Factoriser $T = ax^2+bx+c$: Discriminant: $\Delta = b^2 - 4ac$ $\Delta \lt 0$ impossible! $\Delta = 0$ : $T = a(x+\frac{b}{2a})^2$ $\Delta \gt 0$ : $T =a(x-x_1)(x-x_2)$ avec $x_1 = \frac{-b+\sqrt \Delta}{2a}$ ; $x_2 =\frac{-b-\sqrt \Delta}{2a} \}$

Go ! Factoriser: !

 $2x^2 - x - 6 =$ $2(x-\frac{3}{2})(x-2) \;\;\;\;\;\;\;\;(\Delta > 0)$ $2x^2 - 3x +\frac{9}{0} =$ $2(x- \frac{3}{4})^2 \;\;\;\;\;\;\;\; (\Delta = 0)$ $x^2 +3x +10 =$ $\Delta = -31 \;\;\;\;\;\;\;\;$ impossible !