Answer:
[tex]\large\boxed{x=-4\ \vee\ x=7}[/tex]
Step-by-step explanation:
[tex]x^2-3x-28=0\\\\x^2+4x-7x-28=0\\\\x(x+4)-7(x+4)=0\\\\(x+4)(x-7)=0\iff x+4=0\ \vee\ x-7=0\\\\x+4=0\qquad\text{subtract 4 from both sides}\\x=-4\\\\x-7=0\qquad\text{add 7 to both sides}\\x=7[/tex]
