Subject

Mathematics

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsLong Answer Type

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31.

Evaluate: sin x + cos x16 + 9 sin 2x dx


Let I = sin x  + cos x16 + 9 2x dx

Here, we express the denominator in terms of sin x - cos x which is the integration of numerator.

Clearly,

(sin x  - cos x)2 = sin2 x + cos2 x - 2 sin xcos x = 1-sin 2x sin 2 x  = 1 - (sin x - cos x)2 I = 0π/4sin x  + cos x16 + 9 1 - (sin x - cos x)2 dx I = 0π/4sin x + cos x25-9 (sin x - cos x)2 dxLet sin x - cosx = t,Then , d (sin x - cos x) = dt (cos x + sin x ) dx = dtalso, x = 0 t = sin 0 - cos 0  = - 1and  x = π4t = sin π4 - cos π4 = 0 I= -10 dt25-9t2 = 19-10 dt259-t2 =19 -10dt532-t2 I = I9 x 12 (5/3) log 53 + t5/3 - t-10 I=130log - 1 log 2/38/3  = 130 log 1 - log 14 = 130 [ log 1 + log 4 ]  = 130 log 4  = 115 log 2 


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32.

A factory manufactures two types of screws A and B, each type requiring the use of two machines, an automatic and a hand - operated. It takes 4 minutes on the automatic and 6 minutes on the hand-operated machines to manufacture a packet of screws ‘B’. Each machine is available for at most 4 hours on any day. The manufacturer can sell a packet of screws ‘A’ at a profit of 70 paise and screws ‘B’ at a profit of Rs. 1. Assuming that he can sell all the screws he manufactures, how many packets of each type should the factory owner produce in a day in order to maximize his profit? Formulate the above LPP and solve it graphically and find the maximum profit.


33.

Evaluate:13(x2 + 3x + ex) dx


34.

Using integration, find the area of the region in the first quadrant enclosed by the x-axis, the line y = x and the circle x2 + y2 =32


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35.

Find the distance of the point (-1,-51-10) from the point of intersection of the line r = 2i^ -j^ + 2k^ + λ (3i^ + 4j^ + 2k^) and the plane r. (i^-j^ + k^) = 5


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