Subject

Mathematics

Class

CBSE Class 12

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

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 Multiple Choice QuestionsShort Answer Type

1.

If A is a 3 × 3 invertible matrix, then what will be the value of k if det(A–1) = (det A)k.

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2.

Determine the value of the constant ‘k’ so that the function  is continuous at x = 0.

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3.

If a line makes angles 90° and 60° respectively with the positive directions of x and y axes, find the angle which it makes with the positive direction of the z-axis.

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4.

Show that all the diagonal elements of a skew symmetric matrix are zero.

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5.
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6.

The volume of a sphere is increasing at the rate of 3 cubic centimetres per second. Find the rate of increase of its surface area, when the radius is 2 cm.


straight V space equals 4 over 3 πr cubed
rightwards double arrow space dV over dt space equals space 4 over 3 straight pi.3 straight r squared dr over dt
rightwards double arrow space dV over dt space equals space 4 πr squared dr over dt
rightwards double arrow dr over dt space equals space fraction numerator 1 over denominator 4 πr squared end fraction dV over dt
rightwards double arrow dr over dt space equals space fraction numerator 3 over denominator 4 straight pi left parenthesis 2 right parenthesis squared end fraction
open square brackets straight r equals space 2 space cm space and space dV over dt space equals space 3 space cm squared divided by sec close square brackets

rightwards double arrow dr over dt space space equals fraction numerator 3 over denominator 16 space straight pi end fraction cm divided by sec

Now, let S be the surface area of the sphere at any time t. then,
S = 4πr2
rightwards double arrow space dS over dt space equals space 8 πr dr over dt
rightwards double arrow space dS over dt space equals space 8 straight pi space left parenthesis 2 right parenthesis space straight x fraction numerator 3 over denominator 16 straight pi end fraction
open square brackets straight r space equals 2 space cm space and space dr over dt space equals space fraction numerator 3 over denominator 16 straight pi end fraction space cm divided by sec close square brackets
rightwards double arrow space dS over dt space equals space 3 space cm squared divided by sec



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7.

Show that the function f(x) = 4x3 – 18x2 + 27x – 7 is always increasing on R.

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8.

Prove that 

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9.

Using properties of determinants, prove that 

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10.

Let find a matrix D such that CD – AB = O.

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