Question

A 2 - a - 20 help me out please

Answer 1

Hey there,

By using the $AC$ method . . . 

$x^{2} +bx+c$

We do $(a^{2} -a-20)$ using the 
$AC$ method, and from this, our
answer would give us . . . 


$(a-5) \ (a+4)$

Hope this helps.
~Jurgen