Subject

Mathematics

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsLong Answer Type

11.

Show that the height of the cylinder of maximum volume, which can be inscribed in a sphere of radius R is  Also find the maximum volume. 

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12.

Find the equation of the normal at a point on the curve x2 = 4y which passes through the point (1, 2). Also, find the equation of the corresponding tangent.

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 Multiple Choice QuestionsShort Answer Type

13.

Write the degree of the differential equation straight x cubed open parentheses fraction numerator straight d squared straight y over denominator dx squared end fraction close parentheses squared space plus space open parentheses dy over dx close parentheses to the power of 4 space equals space 0

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14.

If a unit vector straight a with rightwards arrow on top space equals space straight x straight i with hat on top plus 2 straight j with hat on top minus straight z straight k with hat on top and straight b with rightwards arrow on top space equals space 3 straight i with hat on top minus straight y straight j with hat on top plus straight k with hat on top are two equal vectors, then write the value of x+y+z.

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15.

If a unit vector straight a with rightwards arrow on top makes angle straight pi over 3 space with space straight i with hat on top comma space space space straight pi over 4 space with space straight j with hat on top space and space acute space angle space straight theta space with space straight k with hat on top comma space then find the value of straight theta.

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16.

Find the Cartesian equation of the line passes through the point (-2, 4, -5) and is parallel to the line fraction numerator straight x plus 3 over denominator 3 end fraction equals fraction numerator 4 minus straight y over denominator 5 end fraction equals fraction numerator straight z plus 8 over denominator 6 end fraction.

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17.

The amount of pollution content added in air in city due to x-diesel vehicles is given by straight P left parenthesis straight x right parenthesis space equals space 0.005 straight x cubed plus 0.02 straight x squared plus 30 straight x. Find the marginal increase in pollution content when 3 diesel vehicles are added and write which value is indicated in the above questions.

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18.

Show that the function f in straight A space equals space straight R to the power of minus open curly brackets 2 over 3 close curly brackets space defined space as space straight f left parenthesis straight x right parenthesis space equals space fraction numerator 4 straight x plus 3 over denominator 6 straight x minus 4 end fraction space is space one minus one space and space onto. space Hence space find space straight f to the power of negative 1 end exponent.

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19.

Differentiate the following function with respect to x:
left parenthesis log space straight x right parenthesis to the power of straight x plus straight x to the power of log straight x


 Let space straight y space equals left parenthesis logx right parenthesis to the power of straight x plus straight x to the power of logx space space space space space space space space... left parenthesis 1 right parenthesis
Now space let space straight y subscript 1 equals left parenthesis log space straight x right parenthesis to the power of straight x space and space straight y subscript 2 equals straight x to the power of logx
rightwards double arrow space space straight y space equals space straight y subscript 1 plus straight y subscript 2 space space space space space space space space space space space space space space space space... left parenthesis 2 right parenthesis
Differentiating (2), w.r.t.x, 
dy over dx equals dy subscript 1 over dx plus dy subscript 2 over dx space space space space space space space space space space... left parenthesis 3 right parenthesis

Now consider straight y subscript 1 space equals space left parenthesis log space straight x right parenthesis to the power of straight x
Taking log on both sides,
logy subscript 1 space equals space straight x space log left parenthesis log space straight x right parenthesis
Differentiating, w.r.t.x, we get
1 over straight y subscript 1 dy subscript 1 over dx equals straight x cross times 1 over logx cross times 1 over straight x plus 1 cross times log left parenthesis log space straight x right parenthesis
rightwards double arrow space space dy subscript 1 over dx space equals space straight y subscript 1 open parentheses 1 over logx plus log left parenthesis log space straight x right parenthesis close parentheses
rightwards double arrow dy subscript 1 over dx equals left parenthesis logx right parenthesis to the power of straight x open parentheses fraction numerator 1 over denominator log space straight x end fraction plus log space left parenthesis log space straight x right parenthesis close parentheses space space space space space space... left parenthesis 4 right parenthesis
Now comma space consider space straight y subscript 2 space equals straight x to the power of logx
logy subscript 2 space equals space left parenthesis log space straight x right parenthesis left parenthesis log space straight x right parenthesis space equals left parenthesis log space straight x right parenthesis squared
Differentiating space straight w. straight r. straight t. straight x comma space we space get
1 over straight y subscript 2 dy subscript 2 over dx equals 2 left parenthesis log space straight x right parenthesis cross times 1 over straight x
rightwards double arrow space dy subscript 2 over dx space equals straight y subscript 2 open parentheses fraction numerator 2 logx over denominator straight x end fraction close parentheses equals straight x to the power of logx open parentheses fraction numerator 2 logx over denominator straight x end fraction close parentheses... left parenthesis 5 right parenthesis
Using equations (3), (4) and (5), we get:
dy over dx equals left parenthesis log space straight x right parenthesis to the power of straight x open square brackets 1 over logx plus log left parenthesis log space straight x right parenthesis close square brackets plus straight x to the power of logx open parentheses fraction numerator 2 logx over denominator straight x end fraction close parentheses

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20. If space straight y space equals space log space open square brackets straight x space plus space square root of straight x squared plus space straight a squared end root close square brackets comma space show space that space left parenthesis straight x squared space plus space straight a squared right parenthesis space fraction numerator straight d squared straight y over denominator dx squared end fraction space plus straight x dy over dx space equals space 0
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