1. 3(a^3-1)=3(a-1)(a^2+a+1)
2. y(y^2-1)=y(y-1)(y+1)
3. mn(m^2-n^2)=mn(m-n)(m+n)
4. 2a(a^2-b^2)=2a(a-b)(a+b)
1. x^2y^2(x^2-y^2)=x^2y^2(x-y)(x+y)
2. 7c^2(d^2-9b^2)=7c^2(d-3b)(d+3b)
3. 8(1-9x^6y^2)=8(1-3x^3y)(1+3x^3y)
4. 2a^2b(16a^2-1)=2a^2b(4a-1)(4a+1)