1) a³-a²b-ab+a²

(a³+a²)+(-a²b-ab)

a²(a+1)-ab(a+1)

(a²-ab)(a+1)

2) x²-2xy+y²-81

(x-y)²- 9²

(x-y+9)(x-y-9)

3)100-4x²-4xy-y²

10²-(2x-y)²

(10-2x-y)(10+2x-y)

4)216-a³

6³-a³

(6-a)(36+6a+a²)

5)27x³+125y³

(3x)³+(5y)³

(3x+5y)(9x²-15xy+25y²)

^o^ meow <3