|a| = [tex] \left \{ {{a,a \geq 0} \atop {-a,a\ \textless \ 0}} \right. [/tex]
1) 3-6y=12
-6y=9
y= -[tex] \frac{9}{6} [/tex] = -[tex] \frac{3}{2} [/tex]
2) 3-6y= -12
-6y=-15
y= [tex] \frac{15}{6} [/tex]
y= [tex] \frac{5}{2} [/tex]
Deci y∈{ -[tex] \frac{3}{2} [/tex] ; [tex] \frac{5}{2} [/tex] }
