[tex]a)\\\\x^2-49=0\\\\(x-7)(x+7)=0\\\\x-7=0\ \ lub\ \ x+7=0\\\\x=7\ \ lub\ \ x=-7\\\\x\in\left\{ \-7,7\right\}[/tex]
[tex]b)\\\\2(x-2)(x+3)=0\\\\x-2=0\ \ lub\ \ x+3=0\\\\x=2\ \ lub\ \ x=-3\\\\x\in\left\{ \-3,2\right\}[/tex]
[tex]c)\\\\x(x-100)=0\\\\x=0\ \ lub\ \ x-100=0\\\\x=0\ \ lub\ \ x=100\\\\x\in\left\{ 0,100\right\}[/tex]
