7. Calculează, reducând termenii asemenea:
a) (x + 2)(x + 3);
b) (x - 1)(x – 4);
c) (x - 3)(x + 4);
d) (x + 5)(x - 1);
e) (2x + 1)(3x + 2);
f) (4x – 1)(5x + 2);
g) (1 - x)(3x + 1);
h) (4x + 1)(5x – 2)​