a) A = x² - 1 + x² - 2x + 1 = 2x² - 2x
b) A = 2x(x-1)
c) P = 2.2/4 - 2rac(2)/2 = 1 - rac(2)
d) Q = 1 + rac(2)
e) P.Q = (1- rac(2))(1 + rac(2)) = 1-2 = -1
f) (1- rac(2))² - 2.((1- rac(2)) = (1- rac(2))(1-rac(2)-2) = (1- rac(2))(-1-rac(2)) = -(1- rac(2))(1+rac(2))
= -(1-2) = 1 OK
(1+rac(2))² - 2(1+rac(2)) = (1+rac(2))(1 + rac(2) - 2) = (1+rac(2))(rac(2)-1) = 2 -1 = 1 OK
