(2ab)²×(a²-b²)-(2a²b²)²÷(4b²)+4a²b^4
=4a²b²×(a²-b²)-4a^4b^4÷(4b²)+4a²b^4
=4a^4b²-4a²b^4-a^4b²+4a²b^4
=3a^4b²