Answer:
x = -2 or x = 10
Step-by-step explanation:
[tex]x^2-8x-20=0\\\\x^2+2x-10x-20=0\\\\x(x+2)-10(x+2)=0\\\\(x+2)(x-10)=0\iff x+2=0\ \vee\ x-10=0\\\\x+2=0\qquad\text{subtract 2 from both sides}\\\boxed{x=-2}\\\\x-10=0\qquad\text{add 10 to both sides}\\\boxed{x=10}[/tex]
