亦难幸福北大版高等数学课后答案第七章
u=2x+y,v=x y. 7 2
I=4du 1(uv)1 √22.(x+
.
x=
u+v
3
,
D(x,y)
3.
4
.
D
y
xy.
u
x=
v
52
D(u,v)
= 2v
dv=8+
I=
2
·
π
4.x2
b2
D
D
答
26.
2
a>0,
2
2
I(a)=
e xdx,J(a)=
aw
2
a
案
4(a
2
+b2)ab.
网
.x=arcosθ,y=brsinθ.
D(x,y)
Da
后
x+y≤a,x≥0,y≥0}.
x2 y2
(1)[I(a)]2=edxdy,
Ra={(x,y)|0≤x≤a,0≤y≤a};
khd
2a,
课
√
(2)J(a)≤[I(a)]2≤J(
Ra
w.
π
2
dθ
a
Da
e x
π
2
y2
dxdy≤
Ra
e rrdr=
2
π
ww
3
.co
≤1.e x
2
2.x=u+1
I=D′(v+1 224.(x+y2)dxdy,
1
2
4.
2.
D(x,y)
2,
y2
dxdy,
Da={(x,y)|
π
e x
2
y2
dxdy≤
D√
2a)=
m
15.
2
+rcosθ,y= 2πdr0(1
1
D(u,v)
=r.
