[tex]\left \{ {{7x+6\:\:\:\:\:\:x<0} \atop {7x+12\:\:\:\:x\geq 0}} \right.[/tex]
[tex]f(-1)[/tex]
Solve
[tex]-7\cdot \:1+6x<0[/tex] Swap the negative sign
[tex]-7+6x<0[/tex] Multiply the numbers
[tex]-7+6x+7<0+7[/tex] Add 7 to both sides
[tex]6x<7[/tex] Simplify
[tex]\frac{6x}{6}<\frac{7}{6}[/tex] Divide both sides by 6
[tex]x<\frac{7}{6}[/tex] Simplify
[tex]-7\cdot \:1+12x<0[/tex] Swap the negative sign
[tex]-7+12x<0[/tex] Multiply the numbers
[tex]-7+12x+7<0+7[/tex] Add 7 to both sides
[tex]12x<7[/tex] Simplify
[tex]\frac{12x}{12}<\frac{7}{12}[/tex] Divide both sides by 12
[tex]x<\frac{7}{6}[/tex] Simplify
