Subject

Mathematics

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

21.

The scalar product of the vector straight a with rightwards arrow on top equals space straight i with hat on top plus straight j with hat on top plus straight k with hat on top with a unit vector along the sum of vectors straight b with rightwards arrow on top equals 2 straight i with hat on top plus 4 straight j with hat on top minus 5 straight k with hat on top space space and space straight c with rightwards arrow on top space equals space straight lambda straight i with hat on top plus 2 straight j with hat on top plus 3 straight k with hat on top is equal to one. Find the value of straight lambda and hence find the unit vector along straight b with rightwards arrow on top plus straight c with rightwards arrow on top.

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22. Evaluate colon
integral subscript 0 superscript straight pi fraction numerator 4 straight x space sinx over denominator 1 plus cos squared straight x end fraction dx
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23.

Evaluate:
integral fraction numerator straight x plus 2 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx

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24.

An experiment succeeds thrice as often as it fails. Find the probability that in the next five trials, there will be at least 3 successes.

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25. If space straight y space equals space Pe to the power of ax plus Qe to the power of bx show that
straight d to the power of 2 straight y end exponent over dx squared minus left parenthesis straight a plus straight b right parenthesis dy over dx plus aby space equals 0
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26. If space straight x equals cost left parenthesis 3 minus 2 cos squared straight t right parenthesis space and space straight y equals sint left parenthesis 3 minus 2 sin squared straight t right parenthesis comma space find space the space value space of space dy over dx at space straight t equals straight pi over 4.
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27.

Find the particular solution of the differential equation log open parentheses dy over dx close parentheses equals 3 straight x plus 4 straight y comma space given space that space straight y space equals space 0 comma space when space straight x equals space 0.

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28.

Find the value of p, so that the lines:
are perpendicular to each other. Also find the equations of a line passing through a point (3, 2, -4) and parallel to line l1.

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 Multiple Choice QuestionsLong Answer Type

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29.

Find the equation of the plane through the line of intersection of the planes x + y + z = 1 and 2x + 3y + 4z = 5 which is perpendicular to the plane x- y + z = 0. Also find the distance of the plane obtained above, from the origin.


Equation of the plane passing through the intersection of the planes x+y+z=1 and 2x+3y+4z=5 is:
left parenthesis straight x plus straight y plus straight z minus 1 right parenthesis plus straight lambda left parenthesis 2 straight x plus 3 straight y plus 4 straight z minus 5 right parenthesis space equals space 0
left parenthesis 1 plus 2 straight lambda right parenthesis straight x plus left parenthesis 1 plus 3 straight lambda right parenthesis straight y plus left parenthesis 1 plus 4 straight lambda right parenthesis straight z minus left parenthesis 1 plus 5 straight lambda right parenthesis equals 0
This space plane space space has space to space be space perpendicular space to space the space plane space straight x minus straight y plus straight z space equals space 0.
Thus comma
left parenthesis 1 plus 2 straight lambda right parenthesis 1 plus left parenthesis 1 plus 3 straight lambda right parenthesis left parenthesis negative 1 right parenthesis plus left parenthesis 1 plus 4 straight lambda right parenthesis 1 equals space 0
1 plus 2 straight lambda minus 1 minus 3 straight lambda plus 1 plus 4 straight lambda space equals space 0
1 plus 3 straight lambda space equals space 0
straight lambda equals negative 1 third
Thus, the equation of the plane is:
open parentheses 1 plus 2 open parentheses negative 1 third close parentheses close parentheses straight x plus open parentheses 1 plus 3 open parentheses negative 1 third close parentheses close parentheses straight y plus open parentheses 1 plus 4 open parentheses negative 1 third close parentheses close parentheses straight z minus open parentheses 1 plus 5 open parentheses negative 1 third close parentheses close parentheses equals space 0
open parentheses 1 minus 2 over 3 close parentheses straight x plus left parenthesis 1 minus 1 right parenthesis straight y plus open parentheses 1 minus 4 over 3 close parentheses straight z minus open parentheses 1 minus 5 over 3 close parentheses equals 0
straight x over 3 minus straight z over 3 plus 2 over 3 equals 0
straight x minus straight z equals negative 2
Thus comma space the space distance space of space this space plance space from space the space origin space is colon
open vertical bar fraction numerator negative left parenthesis negative 2 right parenthesis over denominator square root of 1 squared plus 0 squared plus 1 squared end root end fraction close vertical bar space equals space open vertical bar fraction numerator 2 over denominator square root of 2 end fraction close vertical bar equals space square root of 2

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30.

Find the distance of the point (2, 12, 5) from the point of intersection of the line 
straight r with rightwards arrow on top equals 2 straight i with hat on top minus 4 straight j with hat on top plus 2 straight k with hat on top plus straight lambda open parentheses 3 straight i with hat on top plus 4 straight j with hat on top plus 2 straight k with hat on top close parentheses space and space the space plane space straight r with rightwards arrow on top. open parentheses straight i with hat on top minus 2 straight j with hat on top plus straight k with hat on top close parentheses equals 0.

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