Упростить. (3а-b)²-(a-b)(a+b)

Question

Упростить.
(3а-b)²-(a-b)(a+b)

Answer 1

9а²-в²-(а²+ав-ав-в²) = 9а²-в²-а²-ав+ав+в² = 8а²

Answer 2

= 9a^2 - 6ab+b^2-a^2+b^2=10a^2-6ab+2b^2