Resposta:
a)
[tex]x^{2} -x=0\\x.(x-1)=0\\\left \{ {{x=0} \atop {x-1=0}} \right.\\\\\left \{ {{x=0} \atop {x=1}} \right. \\x_{1} =0,x_{2} =1[/tex]
b)
[tex]30x^{2} -60x=0\\30x.(x-2)=0\\x.(x-2)=0\\\left \{ {{x=0} \atop {x-2=0}} \right. \\\left \{ {{x=0} \atop {x=2}} \right. \\x_{1} =0,x_{2} =2[/tex]
