Answer:
[tex](x+10)(x-2)[/tex]
Step-by-step explanation:
[tex]x^2+8x-20=\\\\(x+10)(x-2)[/tex]
You can confirm this by working backwards, expanding:
[tex](x+10)(x-2)=\\\\x^2+10x-2x-20=\\\\x^2+8x-20[/tex]
Hope this helps!