Respuesta :
A.
thinking...
12^2=144
signs different therefore the 12 cancels out (no middle term)
signs different sign is negative
hope this helps
thinking...
12^2=144
signs different therefore the 12 cancels out (no middle term)
signs different sign is negative
hope this helps
I don't understand what you mean by 'mentally' but anyways, here is how to solve it.
(z−12)(z+12)
=(z+−12)(z+12)
=(z)(z)+(z)(12)+(−12)(z)+(−12)(12)
=z^2+12z−12z−144
=z^2−144
(z−12)(z+12)
=(z+−12)(z+12)
=(z)(z)+(z)(12)+(−12)(z)+(−12)(12)
=z^2+12z−12z−144
=z^2−144
