16 MULTIPLE INTEGRALS
16 MULTIPLE INTEGRALS
16 MULTIPLE INTEGRALS
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CHAPTER <strong>16</strong><br />
SAMPLE EXAM SOLUTIONS<br />
(a)<br />
(b) The Jacobian is<br />
∂x/∂u ∂x/∂v<br />
∣<br />
∣∣ ∂y/∂u ∂y/∂v ∣<br />
∫∫S (3x + 2y) dA = ∫ 1<br />
0<br />
= 3 ∫ 1<br />
0<br />
∣∣ ∣∣∣ ∣∣∣<br />
∣ = 2 1<br />
1 2 ∣∣ = 3, so<br />
∫ 1<br />
0<br />
[3 (2u + v) + 2 (u + 2v)] 3 du dv<br />
[<br />
1<br />
3u 2 + 3uv + u 2 + 4uv] dv<br />
0<br />
= 3 ∫ 1<br />
0 (3 + 3v + 1 + 4v) dv = 3 [<br />
4v + 7 2 v2] 1<br />
0 = 45 2<br />
<strong>16</strong>.<br />
∫ 9<br />
1<br />
17. (a)<br />
∫ π/2 ∫ π/4<br />
0 π/6 ρ2 sin φ dφ dθ dρ = π 2<br />
=<br />
∫ 9 [<br />
1 −ρ 2 cos φ ] π/4<br />
[<br />
13<br />
ρ 3] 9<br />
√<br />
3 −<br />
√<br />
2<br />
2<br />
π/6 dρ = π 2<br />
= 182<br />
1<br />
3<br />
∫ √ √ 9 3 − 2<br />
1<br />
( √3<br />
−<br />
√<br />
2<br />
)<br />
π<br />
2<br />
ρ 2 dρ<br />
T maps the unit square in the uv-plane to the unit circle in the xy-plane.<br />
(b) The area of S is π.<br />
∫ 1 ∫ 1 ∫ 1<br />
−1 −1<br />
(ax + by) dydx<br />
−1<br />
2ax dx<br />
18. f ave = ∫ 1 ∫ 1<br />
−1 −1 1 dydx =<br />
= 0<br />
4<br />
939