Question

Simplify
$(a+b+c)(a+b-c)$.

Answer 1

$(a+b+c)(c+b-c)$

Expand $(a+b+c)(a+b-c)$ by multiplying

each term in first expression by each term in second expression

$a^2+ab-ac+ba+b^2-bc+ca+cb-c^2$

$a^2+ab+ba+b^2-ac+ca+cb-bc-c^2$

$a^2+2ab+b^2-0+0-c^2$

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

$(a+b{)}^2-c^2$