12. Упростите.


2) (x + 3) ^ 2 - (x - 3)(x + 3)


4) (- a - b)(a + b) - (a + b)(a - b)


6) (- 3a - 1) ^ 2 - (3a - 1)(3a + 1)


10) (a - c)(a + c) -(-b+c)(-b-c


8) (x + 4)(x + 2) - (x - 3)(x + 3)


9) (a + b)(a - b) - (a + b) ^ 2 + (a - b) ^ 2


7) (2x + 4)(2x - 4) - (2x + 5)(2x - 5)


5) (5a - 7)(5a + 7) - 25 * (a - 2) ^ 2


3) (2x - 5y)(2x + 5y) - (2x - 5y) ^ 2


1) (x - 2) ^ 2 - (x + 2)(x - 2)