设L是圆周x2+y2=a2(a>0)负向一周,则曲线积分(x3-x2y)dx+(xy3-y3)dy的值为:()
A . πa4
B . -πa4
C . -(π/2)a4
D . (π/2)a4
[单选题]设C为圆周x2+y2=ax(a>0),则曲线积分的值是().A . a2B . 2a2C . 3a2D . 4a2
[单选题]L是区域D:x2+y2≤-2x的正向周界,则(x3-y)dx+(x-y2)dy等于:()A . 2πB . 0C . (3/2)πD . -2π
[单选题]设L是由圆周x2+y2=a2,直线x=y,及x轴在第一象限中所围成的图形的边界,则的值是:()A . 2(ea-1)B . (πa/4)eaC . 2(ea-1)+(πa/4)eaD . (1/2)(ea-1)+πaea
[单选题]方程(x2+y)dx+(x-2y)dy=0的通解是().A . B . C . D .
[单选题]已知函数的全微分df(x,y)=(3x2+4xy-y2+1)dx+(2x2-2xy+3y2-1)dy,则f(x,y)等于( ).A.B.C.D.
[单选题]已知函数的全微分df(x,y)=(3x2+4xy-y2+1)dx+(2x2-2xy+3y2-1)dy,则f(x,y)等于( ).A.B.C.D.
[单选题]已知函数的全微分df(x,y)=(3x2+4xy-y2+1)dx+(2x2-2xy+3y2-1)dy,则f(x,y)等于( ).A.B.C.D.
[单选题]如x⊕y=x2+y2,则3⊕1⊕3=( )。A.109B.100C.120D.160
[单选题]如x⊕y=x2+y2,则3⊕1⊕3=( )。A.109B.100C.120D.160
[单选题]如x⊕y=x2+y2,则3⊕1⊕3=( )。A.109B.100C.120D.160