1/2(x+y)^5+2(x+y)^2-4/3(x+y)^3-1/2(x+y)^5+1/3(x+y)^3,其中x=3-y_数学解答

1/2(x+y)^5+2(x+y)^2-4/3(x+y)^3-1/2(x+y)^5+1/3(x+y)^3,其中x=3-y

人气：172 ℃　时间：2020-04-13 20:23:28

解答

1/2(x+y)^5+2(x+y)^2-4/3(x+y)^3-1/2(x+y)^5+1/3(x+y)^3
=-(x+y)³+2(x+y)²
x=3-y
∴x+y=3
∴原式=-3³+2*3²
=-27+18
=-9