A very good day to all.

I have several questions all relating to algebra, and I will be very thankful if you can help me solve them. Please also show your workings clearly so that I may understand wholly. I am sorry if these questions take a lot a time.

Factorise the following:

1.$\displaystyle (x + y)(a + b) - (y + z)(a + b)$

2. $\displaystyle (2x + y)^2 -3(2x + y)$

3. $\displaystyle 5(m - 2n) - (m -2n)^2$

4. $\displaystyle p^2 -9q^2 +6qr -r^2$

5. $\displaystyle 4a^2 -b^2 -2bc -c^2$