Сборник задач по высшей математике 2 том
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r,n:e 06JIacTb HHTerpHpOBaHHH D - 9TO Kpyr x 2 + y2 ~ 16. |
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HaihH HaH60JIbIIIee |
H HaHMeHbIIIee 3Ha'leHHH <PYHKn;HH |
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5 Ha Kpyre x 2+y2 ~ 16 H rrpHMeHHTb on;eHKy H3 cBoiicTBa 2. |
<PYHKn;HH Z = x +y rrpHHHMaeT 3Ha'leHHe0 Ha rrpHMoit x +y = O. Ha rrpHMbIX x + y = C, rrapaJIJIeJIbHbIX rrpHMoit x + y = 0, <PYHKn;HH Z rrpHHHMaeT 3Ha'leHHe C. CJIe,n:oBaTeJIbHO, <PYHKn;HH Z = x + y (a 3Ha'lHT,H <PYHKn;HH J(x,y)) rrpHHHMaeT Ha Kpyre MaKCHMaJIbHOe 3Ha'leHHeB TO'lKeM (2V2, 2V2) (CM. pHC. 14) H MHHHMaJIbHOe 3Ha'leHHe- B TO'lKeN( -2V2, -2V2). IIpH 9TOM
HMeeM J(M) = 4V2-5 H f(N) = -4V2-5. IIoCKOJIbKY rrJIOIn;a,D;b Kpyra paB-
Ha 7rR2 = 167r, TO COrJIacHo CBOitCTBY 2 ,n:BoitHoro HHTef'paJIa(m = -4V2 - |
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-167r(4V2 + 5) ~ !!(x + y - 5) dxdy ~ 167r(4V2 - 5). |
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3.1.2.On;eHHTb HHTerp8.JI
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r.n.e 06JIaCTb HHTerpHpOBaHHH D - |
Kpyr X 2 + y2 ~ 16. |
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TaK KaK 4x2 + y2 - 2 ~ 0, TO On;eHKa CHH3Y 4x2 + y2 - 2 ~ -2, V(x, y) E |
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E ]R2 OqeBH.n.Ha. IIo9ToMY MO:lKHO IIpHHHTb m |
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1(x, y), BOCIIOJIb3yeMcH IIapa- |
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MeTpHqeCKHMH ypaBHeHHHMH OKPY:lKHOCTH: x = 4cost, Y = 4sint, t E [0,2nj. Tor.n.a IIpH JII060M t
1(4cost,4sint) = 64cos2 t + 16sin2 t - |
2 = |
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= 16(sin2 t + cos2 t) + 48 cos2 t - |
2 = 48 cos2 t + 14 ~ 62, |
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T. K. cos2 t ~ 1. BMecTe C 9THM I(x, y) IIpHHHMaeT 3HaqeHHe M = 62 IIpH |
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t = 0, |
T.e. M = 1(4,0) = 62. OTclO.n.a, |
yqHTbIBaH, qTO IIJIOIIIa,II.b S Kpyra |
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x 2 + y2 ~ 16 paBHa 16n, IIOJIyqaeM on;eHKy |
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-32n ~ !!(4x 2 + y2 - |
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3.1.3. |
!!(x + y + 1) dxdy, r.n.e D - |
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3.1.4. |
x + 2y - |
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3.1.5. |
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3.1.6. |
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3.1. 7. |
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3.1.11. |
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3.1.12. |
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3.1.13. |
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3.1.14. |
BhI'IHCJIHTh,n;BOil:HOil: HHTerpaJI 1= !! 1 +X2 |
2 dxdy, r,n;e D - rrpfl- |
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3.1.15. BhI'IHCJIHTh,n;BOil:HOil: HHTerpaJI I = If |
y dxdy /' r,n;e D - |
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KBa.n;paT 0 ~ x ~ 1, 0 ~ y ~ 1.
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1- j1 dx j1 1 d(1 + x 2 + y2) |
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B'bt"tuc.I!um'b aeoi1:no1i U'Hme2pa.l! no aa'H'Ho1i o6.1!acmu D:
3.1.16. |
jj xydxdy, r,n;e D: 0 ~ x ~ 1, 0 ~ y ~ 2. |
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3.1.17. |
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2'r,n;e D: 0 ~ x ~ 1, 0 ~ y ~ 1. |
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(x + y + 1) |
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3.1.18. |
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x dxdy |
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2 'r,n;e D: 0 ~ x ~ 2, |
x ~ y ~ Xv 3. |
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3.1.19. |
If |
dxdy |
2'r,n;e D: 1 ~ x ~ 3, 2 ~ y ~ 5. |
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(x + 2y) |
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3.1.20. |
BblqHCJIHTb HHTerpaJI I = If |
xdxdy |
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2'r,n;e 06JIaCTb D - napa6o- |
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Q Iho6pa3HM 06JIacTb HHTerpHpOBaHHH D (pHC. 15). TaK KaK npHMM y = x
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D onpe,n;eJIHeTCH CHcTeMotl: HepaBeHCTB {ox2~ x ~ 2,
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(arctg 1 - arctg ~) dx = ~ / dx - / arctg ~dx = ~ . x I0 - |
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3.1.21. |
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Y = 0, x = 1, y |
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3.1.22. |
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//(3 -x - y) dxdy, r.n;e D - |
Kpyr x 2 + y2 :::;; 1. |
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1)2 + (y - 1)2 :::;; 1. |
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3.1.23. |
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xy dxdy, r.n;e D - |
Kpyr (x - |
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Jx 2 + y2 dxdy, r.n;e D - |
Kpyr x 2 + y2 - |
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3.1.24. |
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2ax :::;; O. |
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3.1.25. |
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IhMeHHTb nopH.n;oK HHTerpHpoBaHHH B nOBTopHOM HHTerpaJIe |
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3+v'12+4x-x2 |
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a YqHTbIBM npe.n;eJIbI HHTerpHpOBaHHH, npe.n;CTaBHM 06JIacTb D B BH.n;e CHCTeMbI HepaBeHCTB
{ -2:::;; x:::;; 6, |
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y''"I-;:O-2-:-+-47""X-_-X"2 :::;; y :::;; 3 + v'12 + 4x - x 2. |
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rpacpHKH <PYHKU;Hii |
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IIpe.n;CTaBJIHIOT c060ii COOTBeTCTBeHHO HIDKHIOIO H BepXHIOIO nOJIYOKpY:>KHo- |
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CTH OKPY:>KHOCTH (y - |
3)2 = 12 + 4x - x 2, HJIH (x - 2)2 + (y - 3)2 = 16. |
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TaKHM 06pa30M, 06JIacTb HHTerpHpOBaHHH D - |
Kpyr pa,!l;Hyca 4 C u;eHTpoM |
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06JIacTb D MO:lKHO 3aIUI:CaTb TaK: |
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{-I ~ y ~ 7, |
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2 - Jr"16°-----;-(y------,-,3)"""""2 ~ X ~ 2 + J 16 - (y - 3) 2 • |
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2+v'16-(y-3)2 |
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f(x, y) dx. |
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2-v'16-(y-3)2 |
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Puc. 16 |
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'1/2 |
y2/2 |
3.1.26. IhMeHHTb nopH,n;oK HHTerpHpoBaHHH ! dy |
! f(x, y) dx. |
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y2_1 |
a IIpH pa360pe 9Toro npHMepa HCnOJIb3yeM ,n;pyroit rro,n;xo,n;. 06JIaCTb HH- |
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TerpHpOBaHHH D 3a,n;aeTCH CHcTeMoit HepaBeHCTB |
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v'2 ~ y ~ v'2, |
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y2 |
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reOMeTpH'leCKH9TO 03Ha'laeTCJIe,n;yIOuree: Ka:lK,n;M ropH30HTaJIbHaH rrpHMM,
rrpoxo~urM 'lepe3TO'lKHOTpe3Ka [-v'2, v'2] |
OCH Oy, nepeceKaeT CHa'laJIa |
(npH ,n;BH:lKeHHH CJIeBa HarrpaBO) rrapa60JIy X |
= y2 - 1 (Ha30BeM ee JIHHHeit |
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Bxo,n;a B D), a 3aTeM rrapa60JIY X = Y2 (Ha30BeM ee JIHHHeit Bblxo,n;a H3 D) -
CM. pHC. 17.
IIpH nepeMeHe rropH,n;Ka HHTerpHpOBaHHH Hy:lKHO cnpoeKTHpOBaTb 06JIacTb HHTerpHpOBaHHH D Ha ,n;pyryIO OCb (OCb Ox) H o6HapY:lKHTb JIHHHH Bxo,n;a H Bblxo,n;a rrpH ,n;BH:lKeHHH CHH3Y BBepx B,n;OJIb BepTHKaJIbHbIX rrpHMblx.
136
2
IIapa60JIbI x = Y2 H x = y2 - 1 IIepeceKalOTCH B TOqKax B(I, -J2) H
y2
C(I, J2) (.n.eikTBHTeJIbHO, IIpHpaBHHBM ypaBHeHHH IIapa60JI, HMeeM 2 =
== y2 _ 1 ¢} y2 = 2 ¢} Y = ±J2). TaKHM 06Pa30M, IIpoeKIIHH 06JIaCTH D Ha OCb Ox - OTpe30K [-1,1]. 113 pHcYHKa BH.n.HO, qTO Ha yqacTKe x E [-1,0]
TOqKH Bxo.n.a H Bblxo.n.a pacIIOJIO)KeHbI Ha BeTBHX o.n.Hofi IIapa60JIbI, a Ha yqaCTKe x E [0, 1] - Ha BeTBHX pa3HbIX IIapa60JI. CHaqaJIa oIIpe.n.eJIHM BeTBH
3THX IIapa6oJI, peIIIM OTHOCHTeJIbHO y ypaBHeHHH x |
y2 |
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= y2 - 1 H X = 2 |
Ha |
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COOTBeTCTBYIOIIIHX yqacTKax. IIoJIyqaeM: y = ±Vx+1 H Y = ±$x, x |
~ o. |
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IIepBoe paBeHCTBO COOTBeTcTByeT .n.yraM AC (3HaK |
«IIJIIOC») H AB (3HaK |
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«MHHYC»), BTopoe - .n.yraM OC H OB (pHC. 17). TeM caMbIM, 06JIaCTb D |
pa36HBaeTcH Ha TpH OT.n.eJIbHhle 06JIacTH D 1 , D2 H D3 , T. e. D = DI U D2 U D3 , r,ne
D . {-I ~ x ~ 0, |
D . {o ~ x ~ 1, |
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2· -Vx+1 ~ Y ~ -$x; |
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lfCXO.n.Hblfi HHTerpaJI HaIIHIIIeM B BH.n.e .n.BofiHoro |
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H IIpHMeHHH CBoficTBO a,II.,LLHTHBHOCTH .n.BofiHoro HHTerpaJIa, 3aIIHIIIeM OTBeT
II !(x, y) dxdy = |
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Io dx |
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137
3.1.31. BblqHCJIHTb HHTerp8.JIbHOe cpe,n:Hee 3HaqeHHe <PYHKIJ;HH Z |
= 12-:.: |
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3y B 06JIaCTH D, OrpaHHqeHHoit npHMbIMH 12 - 2x - |
3y = 0, |
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x = 0, y = O. |
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06JIacTb D - |
TpeyrOJIbHHK OAB, r,n:e 0(0,0), A(6, 0), B(O, 4) - |
pHC. 18. |
y
x
Puc. 18
ITo onpe,n:eJIeHHIO HHTerp8.JIbHOe cpe,n:Hee 3HaqeHHe <PYHKIJ;HH z(x,y) B
06JIaCTH D paBHO |
~ II z(x,y)dxdy, r,n:e S - nJIOrn;a,n:b 06JIacTH D (CBOit- |
CTBO 3). |
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ITJIOrn;a,n:b S BblqHCJIHeM no <p0pMYJIe nJIOrn;a,n:H npHMoyrOJIbHOrO TpeyrOJIbHHKa: S = !IOAI . lOBI = 12. OCTaeTcH BhlqHCJIHTb HHTerp8.JI no o62a- CTH D, KOTOPYIO MO:lKHO 3a,n:aTb HepaBeHCTBaMH 0 ~ x ~ 6, 0 ~ y ~ 4 - aX. lIMeeM
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TaKHM o6pa30M, HCKOMoe HHTerp8.JIbHOe cpe,n:Hee paBHO 1~, T. e. 4. |
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B'bt"tuc.n,um'b U'Hmeepa.n,'b'H'bte cpea'Hue 3'Ha"te'H'UJI aa'H'H'btx tjjy'Hr.;v,u1J, 6 yr.;a3a'H- 'H'btX o6.n,ac'1nSlx:
3.1.32.!(x,y) = 2x + y, D - TpeyrOJIbHHK OAB C BepIIIMHaMH 0(0,0),
A(0,3), B(3,0).
3.1.33. !(x, y) = x + 6y, D - TpeyrOJIbHHK, OrpaHHqeHHblit npHMbIMH
y = x, y = 5x, x = 1.
138
3.1.34. |
f (x, y) = JR2 - |
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y2, D - |
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3.1.35. |
f(x,y) = x 3 y2, D - |
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OnpeOe.l/,Umb 3'1ta'l> oa'lt'lt'btx u'ltmezpa.l/,oe: |
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3.1.40. |
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3.1.42.II arcsin(x + y) dxdy.
O::;;x::;;l -l::;;y::;;l-x
,4eo1i.'lto1i. U'ltmeZpM II f(x, y) dxdy no 3aOa'lt'lto1i. o6.1/,acmu npeocmaeumb e
D
6uoe noemop'ltozo oey.MSI cnoco6aMu. COe.l/,amb "lepmeJIC o6.1/,acmu u'ltmezpup06a'lt'USl.:
3.1.43.D orpaHFPleHa JIHHHHMH y = 0, x = 5, y = x.
3.1.44.D - TpeyrOJIbHHK C BepWHHaMH B TOqKax A(-1, -1), B (1, 3),
C(2, -4).
3.1.45.D - IIapaJIJIeJIOrpaMM ABCD C BepWHHaMH A( -3,1), B(2, 1),
C(6, 4), D(I,4).
3.1.46.D - Kpyr (x - 2)2 + (y - 3)2 ~ 4.
3.1.47.D OrpaHHqeHa JIHHHHMH y = x2, X = y2.
3.1.48. |
D OrpaHHqeHa JIHHHHMH y = x3 , X + y = 10, x - |
y = 4, y = o. |
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3.1.49. |
I dx I fdy. |
3.1.50. |
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fdy. |
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139