Factorization.. THX!!!

1)99p^2 - (81q^2 - p^2)
=99p^2 - 81q^2 + p^2
=100p^2 - 81q^2
=(10p)^2 - (9q)^2
=(10p + 9q)(10p - 9q)

2)36p^2 - 60pq + 25q^2
=(6p)^2 - 2(6p)(5q) + (5q)^2
=(6p - 5q)^2

3)2y^2 - 18 - 9y
=2y^2 - 9y - 18
=(2y + 3)(y - 6)

4) m^3 - 216n^3
=m^3 - (6n)^3
=(m - 6n)［m^2 + n(6m) + (6n)^2］
=(m - 6n)(m^2 + 6mn + 36n^2)

5) 16 - 24(h - 5k) + 9(h - 5k)^2
=4^2 - 2(4)［3(h - 5k)］+［3(h-5k)］^2
=［4-3(h-5k)］^2
=(4-3h+15k)^2

1. 99p^2 - (81q^2 - p^2)
=99p^2 - 81q^2 + p^2
=100p^2 - 81q^2
=(10p)^2 - (9q)^2
=(10p + 9q)(10p - 9q)

2. 36p^2 - 60pq + 25q^2
=(6p)^2 - 2(6)(5) + (5q)^2
=(6p - 5q)^2

3. 2y^2 - 18 - 9y
=(2y + 3)(y - 6)

4. m^3 - 216n^3
=m^3 - (6n)^3

5. 16 - 24(h - 5k) + 9(h - 5k)^2
=9(h-5k)^2 - 24(h - 5k) + 16
=[3(h-5k)]^2 - 2(3)(4)(h - 5k) + 4^2
=[3(h-5k) - 4]^2
=(3h-15k-4)^2