Question

已知A=2a^2b-ab^2,B=-a^2b+2ab^2。（1）求5A+4B （2）若|a+2|+（3-b）^2=0,求5A+4B的值

（3）试将a^b+ab^2用A与B的式子表达出来

Answer 1

(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

Answer 2

5A+4B =5(2a^2b-ab^2)+4(-a^2b+2ab^2)
=10a²b-5ab²-4a²b+8ab²
=6a²b+3ab²
|a+2|+（3-b）^2=0
a+2=0
3-b=0
∴a=-2
b=3
5A+4B =6a²b+3ab²=72-54=18

a^b+ab^2=A+B