NCERT Solutions
Class 12 - Mathematics Part-1 - Chapter 4: DETERMINANTS
Exercise 4.5

Question. 1

Examine the consistency of the system of equations:

\(x + 2y = 2\)

\(2x + 3y = 3\)

Answer:

Consistent

Question. 2

Examine the consistency of the system of equations:

\(2x - y = 5\)

\(x + y = 4\)

Answer:

Consistent

Question. 3

Examine the consistency of the system of equations:

\(x + 3y = 5\)

\(2x + 6y = 8\)

Answer:

Inconsistent

Question. 4

Examine the consistency of the system of equations:

\(x + y + z = 1\)

\(2x + 3y + 2z = 2\)

\(ax + ay + 2az = 4\)

Answer:

Consistent

Question. 5

Examine the consistency of the system of equations:

\(3x - y - 2z = 2\)

\(2y - z = -1\)

\(3x - 5y = 3\)

Answer:

Inconsistent

Question. 6

Examine the consistency of the system of equations:

\(5x - y + 4z = 5\)

\(2x + 3y + 5z = 2\)

\(5x - 2y + 6z = -1\)

Answer:

Consistent

Question. 7

Solve the system of linear equations, using matrix method:

\(5x + 2y = 4\)

\(7x + 3y = 5\)

Answer:

\(x = 2,\; y = -3\)

Question. 8

Solve the system of linear equations, using matrix method:

\(2x - y = -2\)

\(3x + 4y = 3\)

Answer:

\(x = -\frac{5}{11},\; y = \frac{12}{11}\)

Question. 9

Solve the system of linear equations, using matrix method:

\(4x - 3y = 3\)

\(3x - 5y = 7\)

Answer:

\(x = -\frac{6}{11},\; y = -\frac{19}{11}\)

Question. 10

Solve the system of linear equations, using matrix method:

\(5x + 2y = 3\)

\(3x + 2y = 5\)

Answer:

\(x = -1,\; y = 4\)

Question. 11

Solve the system of linear equations, using matrix method:

\(2x + y + z = 1\)

\(x - 2y - z = \frac{3}{2}\)

\(3y - 5z = 9\)

Answer:

\(x = 1,\; y = \frac{1}{2},\; z = -\frac{3}{2}\)

Question. 12

Solve the system of linear equations, using matrix method:

\(x - y + z = 4\)

\(2x + y - 3z = 0\)

\(x + y + z = 2\)

Answer:

\(x = 2,\; y = -1,\; z = 1\)

Question. 13

Solve the system of linear equations, using matrix method:

\(2x + 3y + 3z = 5\)

\(x - 2y + z = -4\)

\(3x - y - 2z = 3\)

Answer:

\(x = 1,\; y = 2,\; z = -1\)

Question. 14

Solve the system of linear equations, using matrix method:

\(x - y + 2z = 7\)

\(3x + 4y - 5z = -5\)

\(2x - y + 3z = 12\)

Answer:

\(x = 2,\; y = 1,\; z = 3\)

Question. 15

If

\[ A = \begin{bmatrix} 2 & -3 & 5 \\ 3 & 2 & -4 \\ 1 & 1 & -2 \end{bmatrix} \]

find \(A^{-1}\). Using \(A^{-1}\) solve the system of equations

\(2x - 3y + 5z = 11\)

\(3x + 2y - 4z = -5\)

\(x + y - 2z = -3\)

Answer:

\(A^{-1} = \begin{bmatrix} 0 & 1 & -2 \\ -2 & 9 & -23 \\ -1 & 5 & -13 \end{bmatrix}\), \(x = 1,\; y = 2,\; z = 3\)

Question. 16

The cost of 4 kg onion, 3 kg wheat and 2 kg rice is \(\text{₹}60\). The cost of 2 kg onion, 4 kg wheat and 6 kg rice is \(\text{₹}90\). The cost of 6 kg onion 2 kg wheat and 3 kg rice is \(\text{₹}70\). Find cost of each item per kg by matrix method.

Answer:

Cost of onions per kg = \(\text{₹}5\)

Cost of wheat per kg = \(\text{₹}8\)

Cost of rice per kg = \(\text{₹}8\)

NCERT Solutions Class 12 – Mathematics Part-1 – Chapter 4: DETERMINANTS – Exercise 4.5 | Detailed Answers