Question

(a(a+b)-b(a+b) factorizacion

Answer 1

$\left(a\left(a+b\right)-b\left(a+b\right)\right)$
We take:
$a\left(a+b\right)$
And aply the law of the exponents:
$=a^2+ab$
we do the same process at the other side and we get:
$=a^2+ab-ab-b^2$
Now:
$+ab-ab=0$
So we get that:
$=a^2-b^2$