Question

(a+b+c) (a+b-c) simplify​

Answer 1

$\left(a+b+c\right)\left(a+b-c\right)$

$=aa+ab+a\left(-c\right)+ba+bb+b\left(-c\right)+ca+cb+c\left(-c\right)$

$=aa+ab-ac+ab+bb-bc+ac+bc-cc$

$=2ab+a^2+b^2-c^2$