Rút gọn biểu thức: (x + 2)(x – 2) – (x – 3)(x + 1), (x – 5)^2 + (2x – 3)(x + 4)

Bài 3: Rút gọn Biểu thức: a) (x + 2)(x – 2) – (x – 3)(x + 1) 
b) (x – 5)^2 + (2x – 3)(x + 4)
c) (x^2 – 1)(x + 2) – (x –2)(x62 + 2x + 4)
d) (x–3)(x + 3) – (x – 3)^2
e) (x^2 + 1)(x – 3) – (x – 3)(x^2 + 3x + 9)
f) (2x + 1)^2 + 2(4x^2 – 1) + (2x – 1)^2