Factorise the following.

a) 4 (x + 2) ^2 - 9 (x - 1) ^2

b) 25 (x - 2) ^2 - 16 (x + 3) ^2

A) first expand: (2 (x+2) - 3 (x-1)) x (2 (x+2) + 3 (x-1))

then distribute: (2x+4-3x+3) x (2x+4+3x-3)

add same terms together and subtract numbers: (-x+7) x (5x-1)

final answer: (-x+7) x (5x+1)

b) same steps as before

I. (5 (x-2) - 4 (x+3)) x (5 (x-2) + 4 (x+3))

II. (5x-10-4x-12) x (5x-10+4x+12)

final answer: (x-22) x (9x+2)