a)
[tex]f(x)=4x+12\\\\4x+12=0 \ \ /-12\\\\4x=-12 \ \ /:4\\\\\huge\boxed{x_0=-3}[/tex]
b)
[tex]f(x)=\frac{2}{3}x-\frac{4}{9}\\\\\frac{2}{3}x-\frac{4}{9}=0 \ \ /+\frac{4}{9}\\\\\frac{2}{3}x=\frac{4}{9} \ \ /\cdot\frac{3}{2}\\\\\huge\boxed{x_0=\frac{2}{3}}[/tex]
c)
[tex]f(x)=-\sqrt3x+6\\\\-\sqrt3x+6=0 \ \ /-6\\\\-\sqrt3x=-6 \ \ /\cdot\sqrt3\\\\-3x=-6\sqrt3 \ \ /:(-3)\\\\\huge\boxed{x_0=2\sqrt3}[/tex]
