Question

现有x^2y^2-xy,﹣1/2xy、﹣x^2y^2＋xy三个不同的整式.1.求三个整式的和.2.如果这三个整式中任意选

Answer 1

1

(x^2y^2-xy)+(-1/2xy)+(﹣x^2y^2＋xy)

=x^2y^2-xy-1/2xy-x^2y^2＋xy

=-1/2xy

2

7种

次数最高

(x^2y^2-xy)-(-x^2y^2＋xy)=2x^2y^2-2xy

次数最低

(x^2y^2-xy)+(-x^2y^2＋xy)=0

3

x=4 y=1

x^2y^2-xy=16-4=12

-1/2xy=-2

-x^2y^2+xy=-12

最大值

12+2+12=26

最小值

-12-2-12=-26