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12 Maths CBSE Exam Papers 2015 Chennai Set 1 Answer

Mar 07, 2016

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GeeteshGupta

12 Maths CBSE Exam Papers 2015 Chennai Set 1 Answer12 Maths CBSE Exam Papers 2015 Chennai Set 1 Answer
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  • 2QUESTION PAPER CODE 65/1/MTEXPECTED ANSWERS/VALUE POINTS

    SECTION - A

    1.

    032301210

    or any other correct example + m

    2. Order : 2, degree : 2, Product : 4 + m

    3. xcosBxsinAdxdy

    m

    xsinBxcosAdx

    yd 22

    2

    0ydx

    yd 22

    2

    m

    4. Projection of

    b

    babona m

    Projection 2

    5 m

    5. Value = 3 1 m

    6. Writing drs correctly m

    D.CS 1312,

    134,

    133 m

    Marks

  • 3SECTION - B

    M W C Expenses

    Family expenses

    7.

    230011501050

    200150200

    624312132

    CFamilyBFamilyAFamily

    2 m

    Expenses for family A = 1050Expenses for family B = 1150 1 mExpenses for family C = 2300Any relevant impact 1 m

    8. ztan2ytanxtan 111 1 m

    zcotxy1yxtan 11

    1 m

    0zasz1tan

    xy1yxtan 11

    1 m

    z1

    xy1yx

    m

    xy + yz + zx = 1 m

    9. 0bacacbcba

    R1 R

    1 + R

    2 + R

    3

    (a + b + c) 0bacacb111

    1 m

  • 4C1 C1 C2 , C2 C2 C3

    (a + b + c) 0bbaacaaccb100

    2 m

    (a + b + c) (ab + bc + ca a2 b2 c2) = 0

    given 2acabcabsoc,ba 0cb 22 m

    (a + b + c) = 0 m

    10. Let x =

    dcba

    1 m

    642987

    654321

    dcba

    642987

    6d3c5d2c4dc6b3a5b2a4ba

    1 m

    a + 4b = 7, c + 4d = 2, 2a + 5b = 8, 2c + 5d = 4Solving a = 1, b = 2, c = 2, d = 0 1 m

    02

    21x m

    OR

    2255615

    113A

    existwillA0,1A 1 m

  • 5

    310015102

    Aadj (Any four correct Cofactors : 1 mark) 2 m

    310015102

    AAadjA 1 m

    2255615

    113

    310015102

    AA 1

    100010001

    1 m

    11. 4x3xxf

    4,72

    43,13,27

    xxx

    xx

    1 m

    3x

    3fxflim3xatDH.L.3x

    23x

    2x6lim3x

    3x

    3fxflim3xatDH.R.3x

    03x11

    3xatblediffrentianotisxfDH.R.DH.L. 1 m

  • 6 4x

    4fxflim4xatDH.L.4x

    04x11

    4x

    4fxflim4xatDH.R.4x

    24x

    172xlim4x

    4xatR.H.D4xatDH.L.

    f (x) is not differentiable at x = 4 1 m

    12. 2xexy

    xlogeylog 2x 1 m

    Diff. w. r. t x

    2xexlogx

    edxdy

    y1 22 xx

    2 m

    2

    2

    xx

    exlog2xx

    eydxdy

    m

    xlog2xx1ex 2

    2x xe m

    OR

    yxtanyxlog 122

  • 7Diff. w. r. t. x

    22

    222 ydxdyxy

    yx1

    1dxdy2y2x

    yx21

    2 m

    222

    2

    22 ydxdyxy

    yxy

    yx dx

    dyyx1 m

    xyxydxdy

    m

    xyxy

    dxdy

    m

    13. 1x1xy

    1x21

    1x21

    dxdy

    1 m

    1x21x1x

    2

    m

    22

    2 ydxdy1x4

    m

    dxdy2y

    dxdy8x

    dxyd

    dxdy21x4

    2

    2

    22

    1 m

    4y

    dxdyx

    dxyd1x 2

    22 m

    04y

    dxdyx

    dxyd1x 2

    22 m

  • 814. dxxcos1xcosxcos1

    dxcos1coscos2cos1

    xxxx

    1 m

    xcos1dx2

    xcosdx

    m

    dx2xsecdxxsec 2 1 m

    c2xtan2xtanxseclog 1 m

    15. dxxsinx 1

    dxx1

    x21xsin

    2x

    2

    21

    2

    1 m

    dx

    x11x1

    21xsin

    2x

    2

    21

    2

    m

    dxx1

    dx21dxx1

    21xsin

    2x

    221

    2

    1 m

    cxsin21xsin

    21x1

    2x

    21xsin

    2x 11212

    1

    or cxsin41x1

    4xxsin

    2x 1212

  • 916. dxex2

    0

    12x2

    n2 h m

    .......2h0fh0f0fhlimdxex0h

    2

    0

    12x2

    h1n0f......... 1 m

    22220h 1)(n.......21hhlim

    h1)2(n4h2h .......eee1e 1 m

    6h2nhhnhnhlim

    0h

    m

    +

    1e1ee.h.lim 2h

    2nh

    0h m

    2ee

    38

    2e1e

    38 54

    m

    OR

    0 xcosecxsecdxxtanx

    0

    2 dxxsinx 1 m

    0

    2 dxxsinxILet

  • 10

    0

    2 dxxsinx m

    0

    2 dxxsinx m

    2 I

    0

    0

    2 dx22xcos1dxxsin m

    022xsinx2

    1 m

    22

    I 42

    m

    17. 01z

    11y

    31x

    m

    3

    1z0y

    24x

    m

    1z1,y1, 3x 1 m

    x 13z,0y4, 2

    At the point of intersection

    01, 1 m

    42413so

    Hence the lines are intersecting

    Point of intersection is (4, 0, 1) m

  • 11

    18. Coordinats of Q are 3 +1, 1, 5 +2 m

    D.Rs of 453,2,3PQ

    1 m

    13z4yxplanethetoparallelisPQas

    045334231 1 m

    4 1 m

    OR

    The D.Rs of the line are 2, 6, 4 1 m

    mid point of the line 2, 1, 1 1 m

    The plane passes through (2, 1, 1) and is perpendicular to the

    plane

    eqn. : 2 (x 2) 6 (y 1) + 4 (z + 1) = 0

    x 3y + 2z + 3 = 0 1 m

    Vector from : 03k2j3ir^^^

    1 m

    19. Nos divisible by 6 ..................... = 16 1m

    Nos divisible by 8 ..................... = 12 1m

    Nos not divisible by 24 .............. = 20 1m

    Required probabilty 51

    10020

    1 m

  • 12

    SECTION - C

    20. Ra)(a,,AaeveryFor

    2bydivisibleis0aa

    reflexiveisR 1 m

    Aba,allFor

    bydivisibleisbaRb)(a, 2

    bydivisibleisab 2

    symmetricisRRa)(b, 1 m

    Acb,a,allFor

    bydivisibleisbaRba, 2

    bydivisibleiscbRcb, 2

    2kbaSo, 1 m

    m2ca2cb

    bydivisibleisca 2

    Rc,a transitiveisR 1 m

    and53,1,ofelementsShowing 1 mothereachtorelatedare4}{2,

    othereachtorelatednotare42,and53,1,and 1 m

    21. Graph 2 + 2 m

  • 13

    Area of shaded reigon

    2

    0

    2

    1

    0

    1-dx1x2dxx3dx1xx3 1 m

    2

    1

    22

    0

    20

    1

    2

    21x2

    2x3

    21x2

    unitssq.4191211 1 m

    22. 2x1xy

    222

    x1x1

    dxdy

    2 m

    222

    x1x1xfLet

    0x1x32x0xf 32

    2

    3xor 0x0x3xminormaxFor 2 2 m

    00xatdxf(x)dgCalculatin 2

    2

    03xat 1 m

    maximalocalofpointtheis0x

    0)(0,isptrequiredthe1 m

  • 14

    23. 22

    xxyy

    dxdy

    dxdvxv

    dxdyvx,yLet m

    1vv

    dxdvxv

    2

    1 m

    1vv

    dxdvx

    dvv

    1vx

    dx

    1 m

    dvv11

    xdx

    cvlogvxlog 1 m

    xcyylogxorcxyylog 1 m

    OR

    xtanydxdy2xsin

    2xsinxtan

    x2siny

    dxdy

    1 m

    2

    xsec2xcosecydxdy 2

    xsec21Q2x,cosecP 2

    dx2xcosecdxP

    xtanlog21

  • 15

    xtan1eSo dxP 1 m

    Solution is

    dtxtandxxsec

    txtan

    21

    xtandxxsec

    21

    xtany 22

    1 m

    cxtanxtan

    y 1 m

    Getting 1c m

    xtanxtany m

    24. planeofEqn.

    054z3y2x6zyx 2 m

    11,1,throughpassesit

    1430143 2 m

    bewillplaneofEqn.

    06926z23y20x 1 m

    69k26j23i20r:fromvector^^^

    1 m

  • 16

    25. Let E1 be the event of following course of

    meditation and yoga and E2 be the event of following

    course of drugs 1 m

    21EP,

    21EP 21 1 m

    10040

    10075EAP

    1001004070EAP 21

    1 m

    Formula 1 m

    10075

    21

    10070

    21

    10040

    10070

    21

    10040

    AEP 1

    2 m

    2914

    14570

    26. Let the no. of items in the item A = xLet the no. of items in the item B = y(Maximize) z = 500 x + 150 y 1 m

    60yx

    50,000y500x2500 Graph 2 m

    0yx,

    000,z

    12,5005010,z

    10,0000)(20,z 2 m

    9,00060)(0,z

    12,500Rs.ProfitMax. 1 m

  • 17

    OR

    Let the no. of packets of food X = xLet the no. of packets of food Y = y(minimize) P = (6x + 3y) 1 msubject to

    2403y12x

    46020y4x

    0yx,300,4y6x

    or

    80y4x

    1155yx 2 m

    1502y3x

    0yx,

    Correct pointsof feasibleregion

    A (15, 20), B (40, 15),C (2, 72)So P (15, 20) = 150 P (40, 15) = 285 P (2, 72) = 228

    Graph 2 m

    minimum amount of vitamin A = 150 units when 15 packets of food X and20 packets of food Y are used 1 m