Using elementary tranformation, find the inverse of the matrix :0

Subject

Mathematics

Class

ICSE Class 12

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

21.

A speaks truth in 60% of the cases, while B is 40% of the cases. In what percent of cases are they likely to contradict each other in stating the same fact ?


22.

From a lot of 6 items containing 2 defective items, a sample of 4 items are drawn at random. Let the random variable X denote the number of defective items in the sample. If the sample is drawn without replacement, find :

(a) The probability distribution of X

(b) Mean of X

(c) Variance of X


23.

Find λ if the scalar projection of a = λi^ + j^ + 4k^ on b = 2i^ + 6j^ + 3k^ is 4 units.


24.

The Cartesian equation of line is : 2x - 3 = 3y + 1 = 5 - 6z. Find the vector equation of a line passing through (7, – 5, 0) and parallel to the given line.


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 Multiple Choice QuestionsLong Answer Type

25.

Water is dripping out from a conial funnel of semi-verticle angle π4 at the uniform rate of 2 cm2/sec in the surface, through a tiny hole at the vertex of the bottom. When the slant height of the water level is 4 cm, find the rate of decrease of the slant height of the water.


26.

Using matrices, solve the following system of equations :

2x - 3y + 5z = 11

3x + 2y - 4z = - 5

x + y - 2z = - 3


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27.

Using elementary tranformation, find the inverse of the matrix :

012123311


Let A = 012123311

A= 0[2 - 3] - 1[1 - 9] + 2[1 - 6]

    = 0 + 8 - 10

    = - 2  0

 A- 1 exists.

 A = I.A

012123311 = 100010001.A

Applying R1  R2

123012311 = 010100001.A

Applying R3 - 3R1,

1230120- 5- 8 = 0101000- 31.A

Applying R3 + 5R2,

123012002 = 0101005- 31.A

Applying R2 - R3,

123010002 = 010- 43- 15- 31.A

Applying R1 - 2R2 and Rx 1/2

103010001 = 8- 52- 43- 152- 3212.A

Applying R1 - 3R3,

100010001 = 12- 1212- 43- 152- 3212.A

 

 A- 1 = 121- 11-86- 25 - 31


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28.

A cone is inscribed in a sphere of radius 12 cm. If the volume of the cone is maximum, find its height.


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29.

Evaluate: x - 1x2 - xdx


30.

Evaluate: 0π/2cos2x1 + sinxcosxdx


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