1. (x-3)(x+2)=0 ⇔[tex] \left \{ {{x - 3 = 0} \atop {x+ 2=0}} \right. [/tex][tex] \left \{ {{x = 3} \atop {x= -2}} \right. [/tex] ⇒ x ∈ { -2 ,3}
2. -4x+1+21x=5x-3
- 4x + 21x - 5x = - 3 -1
12x = -4
x = - [tex] \frac{4}{12} [/tex]
x = - [tex] \frac{1}{2} [/tex]
