Answer:
[tex](x-5)(x+4)[/tex]
Step-by-step explanation:
We have the following quadratic equation
[tex]a^2-a-20[/tex]
The factored expression will have the following form
[tex](x+b)(x+c)[/tex]
Where b and c are two real numbers which when added together result in -1, and multiplying them results in -20
[tex]b*c=-20\\b+c=-1[/tex]
You can verify that the numbers that meet this condition are:
-5 and 4
Then the factors are:
[tex](x-5)(x+4)[/tex]