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Consider the system of linear equations ...

Consider the system of linear equations
`x_(1)+2x_(2)+x_(3)=3`
`2x_(1)+3x_(2)+x_(3)=3`
`3x_(1)+5x_(2)+2x_(3)=1`
Then, the system has

A

infinite number of solutions

B

exactly 3 solutions

C

a unique solution

D

no solution

Text Solution

AI Generated Solution

The correct Answer is:
To determine the nature of the solutions for the given system of linear equations, we will follow these steps: ### Step 1: Write the system of equations in matrix form The given system of equations is: 1. \( x_1 + 2x_2 + x_3 = 3 \) 2. \( 2x_1 + 3x_2 + x_3 = 3 \) 3. \( 3x_1 + 5x_2 + 2x_3 = 1 \) We can represent this system in the form of a matrix \( A \) and a vector \( B \): \[ A = \begin{bmatrix} 1 & 2 & 1 \\ 2 & 3 & 1 \\ 3 & 5 & 2 \end{bmatrix}, \quad B = \begin{bmatrix} 3 \\ 3 \\ 1 \end{bmatrix} \] ### Step 2: Calculate the determinant of the coefficient matrix \( A \) We need to calculate the determinant \( \Delta \) of the matrix \( A \): \[ \Delta = \begin{vmatrix} 1 & 2 & 1 \\ 2 & 3 & 1 \\ 3 & 5 & 2 \end{vmatrix} \] Using the determinant formula for a 3x3 matrix: \[ \Delta = a(ei - fh) - b(di - fg) + c(dh - eg) \] where \( a, b, c \) are the elements of the first row, and \( d, e, f, g, h, i \) are the elements of the remaining rows. Calculating: \[ \Delta = 1 \cdot (3 \cdot 2 - 1 \cdot 5) - 2 \cdot (2 \cdot 2 - 1 \cdot 3) + 1 \cdot (2 \cdot 5 - 3 \cdot 3) \] \[ = 1 \cdot (6 - 5) - 2 \cdot (4 - 3) + 1 \cdot (10 - 9) \] \[ = 1 \cdot 1 - 2 \cdot 1 + 1 \cdot 1 \] \[ = 1 - 2 + 1 = 0 \] ### Step 3: Analyze the determinant Since \( \Delta = 0 \), this indicates that the system of equations may either have infinitely many solutions or no solution. ### Step 4: Calculate the determinants of the augmented matrices To further analyze the system, we need to calculate the determinants of the matrices formed by replacing the columns of \( A \) with the vector \( B \). #### Calculate \( \Delta_1 \) Replace the first column of \( A \) with \( B \): \[ \Delta_1 = \begin{vmatrix} 3 & 2 & 1 \\ 3 & 3 & 1 \\ 1 & 5 & 2 \end{vmatrix} \] Calculating \( \Delta_1 \): \[ = 3(3 \cdot 2 - 1 \cdot 5) - 2(3 \cdot 2 - 1 \cdot 3) + 1(3 \cdot 5 - 3 \cdot 3) \] \[ = 3(6 - 5) - 2(6 - 3) + 1(15 - 9) \] \[ = 3 \cdot 1 - 2 \cdot 3 + 1 \cdot 6 \] \[ = 3 - 6 + 6 = 3 \quad (\Delta_1 \neq 0) \] ### Step 5: Conclusion Since \( \Delta = 0 \) and \( \Delta_1 \neq 0 \), the system of equations has no solution. ### Final Answer The system has **no solution**.
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