(1)5A+4B
=5(2a²b-ab²)+4(-a²b+2ab²)
=(10a²b-5ab²)+(-4a²b+8ab²)
=10a²b-5ab²-4a²b+8ab²
=6a²b+3ab²
(2)∵|a+2|+(3-b)²=0
∴a+2=0,3-b=0
∴a=-2,b=3
∴5A+4B
=6a²b+3ab²
=6x(-2)²x3+3x(-2)x3²
=72-54
=18
(3)a²b+ab²=A+B
(1)5A+4B
=5(2a²b-ab²)+4(-a²b+2ab²)
=(10a²b-5ab²)+(-4a²b+8ab²)
=10a²b-5ab²-4a²b+8ab²
=6a²b+3ab²
(2)∵|a+2|+(3-b)²=0
∴a+2=0,3-b=0
∴a=-2,b=3
∴5A+4B
=6a²b+3ab²
=6x(-2)²x3+3x(-2)x3²
=72-54
=18
(3)a²b+ab²=A+B