1) ax^2-ay^2=a(x^2-y^2).

2) x^2y+xy^2-2x-2y=xy(x+y)-2(x+y)=(xy-2)*(x+y).

3) a^3+27=a^3+3^3=1^3(a+3).

4) y-100y^3= y(1-100y^2).

5) 16-y^4= 2^4-y^4=1^4(2-y).

1)ax²-ay²=a(x²-y²)=a(x+y)(x-y)

2)x²y+xy²-2x-2y=xy(x+y)-2(x+y)=(x+y)(xy-2)

3)a³+27=a³+3³=(a+3)(a²-3a+9)

4)y-100y³=y(1-100y²)=y(1+10y)(1-10y)

5)16-yˇ4=2ˇ4-yˇ4=(2²+y²)(2²-y²)=(4+y²)(2+y)(2-y)