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Chapter 4 Determinants Ex 4.6 Solutions

Question - 11 : -

Solve system of linear equations, using matrixmethod.

Answer - 11 : -

The given system of equations can be written inthe form of AX = B, where

Thus, A is non-singular.Therefore, its inverse exists.

Question - 12 : -

Solve system of linear equations, using matrixmethod.

x − y + z = 4

2x + y − 3z =0

x + y + z = 2

Answer - 12 : -

The given system of equations can be written inthe form of AX = B, where

Thus, A is non-singular.Therefore, its inverse exists.

Question - 13 : -

Solve system of linear equations, using matrixmethod.

2x + 3y + 3z =5

x − 2y + z = −4

3x − y − 2z =3

Answer - 13 : -

The given system of equations can be written inthe form AX = B, where

Thus, A is non-singular.Therefore, its inverse exists.

Question - 14 : -

Solve system of linear equations, using matrixmethod.

x − y + 2z = 7

3x + 4y − 5z =−5

2x − y + 3z =12

Answer - 14 : -

The given system of equations can be written inthe form of AX = B, where

Thus, A is non-singular.Therefore, its inverse exists.


Question - 15 : -

If, find A−1.Using A−1 solve the system of equations

Answer - 15 : -


Solution

Now, the given system of equations can bewritten in the form of AX = B, where

Question - 16 : -

The cost of 4 kg onion, 3 kg wheat and 2 kg riceis Rs 60. The cost of 2 kg onion, 4 kgwheat and 6 kg rice is Rs 90. The cost of 6 kgonion 2 kg wheat and 3 kg rice is Rs 70.Find cost of each item per kg by matrix method.

Answer - 16 : -

Let the cost of onions, wheat, and rice per kgbe Rs x, Rs y,and Rs z respectively.

Then, the given situationcan be represented by a system of equations as:

This system of equations can be written in theform of AX = B, where

Now,

X = A−1 B

Hence, the cost of onions is Rs 5 per kg, thecost of wheat is Rs 8 per kg, and the cost of rice is Rs 8 per kg.

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