Subject

Mathematics

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

21.

A line passing through the point A with position vector straight a with rightwards arrow on top space equals space 4 straight i with hat on top plus 2 straight j with hat on top plus 2 straight k with hat on top is parallel to the vector straight b with rightwards arrow on top space equals space 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top. Find the length of the perpendicular drawn on this line from a point p with vector stack straight r subscript 1 with rightwards arrow on top space equals straight i with hat on top plus 2 straight j with hat on top plus 3 straight k with hat on top.

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22. If space straight y space equals space straight e to the power of ax. cosbx comma space then space prove space that
space space space fraction numerator straight d squared straight y over denominator dx squared end fraction minus 2 straight a dy over dx plus left parenthesis straight a squared plus straight b squared right parenthesis straight y space equals space 0
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23. If space straight x to the power of straight x plus straight x to the power of straight y plus straight y to the power of straight x space equals space straight a to the power of straight b comma space space then space find space dy over dx.


straight x to the power of straight x plus straight x to the power of straight y plus straight y to the power of straight x space equals straight a to the power of straight b space space space... left parenthesis straight i right parenthesis
Let space straight u space equals space straight x to the power of straight x
log space straight u space equals space straight x space log space straight x
1 over straight u. du over dx equals straight x.1 over straight x plus log space straight x
therefore space space du over dx equals straight x to the power of straight x left parenthesis 1 plus log space straight x right parenthesis
Let space straight v equals space straight x to the power of straight y
log space straight v space equals space straight y space log space straight x
1 over straight v. dv over dx space equals space open parentheses straight y over straight x plus log space straight x dy over dx close parentheses
therefore space dv over dx equals straight x to the power of straight y open parentheses straight y over straight x plus logx dy over dx close parentheses
Let space straight w space equals straight y to the power of straight x
Log space straight w space equals space straight x space log space straight y
1 over straight w. dw over dx equals space open parentheses straight x over straight y. dy over dx plus log space straight y close parentheses
therefore space dw over dx equals straight y to the power of straight x open parentheses log space straight y space plus space straight x over straight y. dy over dx close parentheses

left parenthesis straight i right parenthesis space can space be space writeen space as
straight u plus straight v plus straight w space equals space straight a to the power of straight b
du over dx plus dv over dx plus dw over dx equals 0
rightwards double arrow space space straight x to the power of straight x left parenthesis 1 plus logx right parenthesis plus straight x to the power of straight y open parentheses straight y over straight x plus logx dy over dx close parentheses plus straight y to the power of straight x open parentheses logy plus straight x over straight y dy over dx close parentheses space equals space 0
rightwards double arrow space space straight x to the power of straight x plus straight x to the power of straight x logx plus straight x to the power of straight y. straight y over straight x plus straight x to the power of straight y. logx. dy over dx plus straight y to the power of straight x. logy plus straight y to the power of straight x. straight x over straight y. dy over dx equals 0
rightwards double arrow space space dy over dx open parentheses straight x to the power of straight y. logx space plus space straight y to the power of straight x. straight x over straight y close parentheses space equals space straight x to the power of straight x plus straight x to the power of straight x logx plus straight x to the power of straight y. straight y over straight x plus straight y to the power of straight x. log space straight y
rightwards double arrow dy over dx open parentheses straight x to the power of straight y. logx space plus space xy to the power of straight x minus 1 end exponent close parentheses space equals space open parentheses straight x to the power of straight x plus straight x to the power of straight x logx plus yx to the power of straight y minus 1 end exponent plus straight y to the power of straight x. log space straight y close parentheses
therefore space space dy over dx equals fraction numerator left parenthesis straight x to the power of straight x plus straight x to the power of straight x logx space plus yx to the power of straight y minus 1 end exponent plus straight y to the power of straight x. log space straight y right parenthesis over denominator left parenthesis straight x to the power of straight y. logx plus xy to the power of straight x minus 1 end exponent right parenthesis end fraction

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24.

If straight x equals straight a space sin space 2 straight t left parenthesis 1 plus cos space 2 straight t right parenthesis space and space straight y space equals straight b space cos space 2 straight t left parenthesis 1 minus cos space 2 straight t right parenthesis comma space then space find dy over dx space at space straight t space equals straight pi over 4.

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25.

Evaluate: integral fraction numerator left parenthesis straight x plus 3 right parenthesis straight e to the power of straight x over denominator left parenthesis straight x plus 5 right parenthesis cubed end fraction dx

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26.

Three schools X, Y, and Z organized a fete (mela) for collecting funds for flood victims in which they sold hand-held fans, mats and toys made from recycled material, the sale price of each being Rs. 25, Rs. 100 andRs. 50 respectively. The following table shows the number of articles of each type sold:
School/Article                     School X                   School Y                School Z
Hand-held fans                         30                         40                         35
      Mats                                  12                         15                         20
       Toys                                 70                         55                         75
Using matrices, find the funds collected by each school by selling the above articles and the total funds collected. Also write any one value generated by the above situation. 

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 Multiple Choice QuestionsLong Answer Type

27.

Sketch the region bounded by the curves straight y equals square root of 5 minus straight x squared end root space and space straight y space equals open vertical bar straight x minus 1 close vertical bar and find its area using integration. 

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28.

Find the particulars solution of the differential equation straight x squared dy space equals space left parenthesis 2 xy plus straight y squared right parenthesis dx comma space given that y =1 when x = 1.

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29.

Find the particulars solution of the differential equation left parenthesis 1 plus straight x squared right parenthesis dy over dx equals open parentheses straight e to the power of straight m space tan to the power of negative 1 straight x end exponent end exponent minus straight y close parentheses comma space given space that space straight y space equals space 1 space when space straight x space equals space 0.

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30.

Show that lines:
straight r with rightwards arrow on top space equals space straight i with hat on top space plus straight j with hat on top space plus straight k with hat on top space plus space straight lambda open parentheses straight i with hat on top minus straight j with hat on top space plus space straight k with hat on top close parentheses
straight r with rightwards arrow on top space equals space 4 straight j with hat on top space plus space 2 straight k with hat on top space plus space straight mu open parentheses 2 straight j with hat on top minus straight j with hat on top plus 3 straight k with hat on top close parentheses space are space coplanar.
Also, find the equation of the plane containing these lines. 

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