Simplify (a^2-2ab+b^2)+(2a^2+2ab+b^2)

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

Remove parentheses.

$a^{2} - 2 a b + b^{2} + 2 a^{2} + 2 a b + b^{2}$

Combine the opposite terms in $a^{2} - 2 a b + b^{2} + 2 a^{2} + 2 a b + b^{2}$ .

Add $- 2 a b$ and $2 a b$ .

$a^{2} + b^{2} + 2 a^{2} + 0 + b^{2}$

Add $a^{2} + b^{2} + 2 a^{2}$ and $0$ .

$a^{2} + b^{2} + 2 a^{2} + b^{2}$

Add $a^{2}$ and $2 a^{2}$ .

$3 a^{2} + b^{2} + b^{2}$

Add $b^{2}$ and $b^{2}$ .

$3 a^{2} + 2 b^{2}$