a³+2ab(a+b)+4b³
=(a+2b)(a²-2ab+b²)+2ab(a+b)-4b³
=0+2ab(a+b)-4b³
=2a²b+2ab²-4b³
=a²b+a²b+2ab²-4b³
=a²b+ab(a+2b)-4b³
=a²b-4b³
=b(a+2b)(a-2b)
=0
a³+2ab(a+b)+4b³
=(a+2b)(a²-2ab+b²)+2ab(a+b)-4b³
=0+2ab(a+b)-4b³
=2a²b+2ab²-4b³
=a²b+a²b+2ab²-4b³
=a²b+ab(a+2b)-4b³
=a²b-4b³
=b(a+2b)(a-2b)
=0