A) - (a-5) (a+3) - (1-a) ²=

c) (2a+0,5) ² - (0,5-2a) ²=

e) 25x² + (7+5x) (7-5x) =

A) - (a-5) (a+3) - (1-a) ^2 = - (a^2+3a-5a-15) - (1-2a+a^2) =

- (a^2 - 2a+15) - (1-2a+a^2) = - a^2 + 2 a - 15 - 1+2a - a^2 =

-2a^2 + 4a - 16 = - 2 (a^2 - 2 a + 8)

C) (2 a + 0.5) ^2 - (0.5 - 2 a) ^2 = (0.5 + 2 a) ^2 - (0. 5 - 2 a) ^2=

0.25 + 2 a + 4 a ^2 - 0.25 + 2 a - 4 a^2 = 4 a.

e) 25 x ^2 + (7+5 x) (7-5x) = 25x^2 + 49-25x^2=49