A=2a²+3ab-b²
B=-½ab
C=(3/2)a³b³-¼a²b⁴
2AB²-C=2(2a²+3ab-b²)(-½ab)²-[(3/2)a³b³-¼a²b⁴]=a⁴b²+(3/2)a³b³-½a²b⁴-[(3/2)a³b³-¼a²b⁴]=a⁴b²-¼a²b⁴
A=2a²+3ab-b²
B=-½ab
C=(3/2)a³b³-¼a²b⁴
2AB²-C=2(2a²+3ab-b²)(-½ab)²-[(3/2)a³b³-¼a²b⁴]=a⁴b²+(3/2)a³b³-½a²b⁴-[(3/2)a³b³-¼a²b⁴]=a⁴b²-¼a²b⁴