2ab—4a^2b^3+o.4a^3b—3ab+6a^2b^3—5.4a^3b,其中a=0.5

题目

2ab—4a^2b^3+o.4a^3b—3ab+6a^2b^3—5.4a^3b,其中a=0.5
b=-3/2

答案

ab=0.5*（-3/2）=-3/4
2ab—4a^2b^3+o.4a^3b—3ab+6a^2b^3—5.4a^3b
=2ab-3ab-4a²b³+6a²b³+0.4a³b-5.4a³b
=-ab+2a²b³-5a³b
=-（-3/4）+2*（ab）²*b-5（ab）a²
=3/4+2（-3/4）²*（-3/2）-5（-3/4）（1/2）²
=3/4-2*9/16*3/2+15/16
=3/4-27/16+15/16
=3/4-12/16
=3/4-3/4
=0