Dive into the world of knowledge and get your queries resolved at IDNLearn.com. Join our community to receive prompt and reliable responses to your questions from knowledgeable professionals.

Use Cramer's Rule to solve the system.

[tex]\[
\begin{array}{l}
\left\{
\begin{array}{ll}
-2x + 4y - 9z = -32 \\
-3x + 5y - 9z = -30 \\
-x + 2y - 3z = -10 \\
\end{array}
\right.
\end{array}
\][/tex]

Given solutions:
[tex]\[ x = -2 \][/tex]
[tex]\[ y = 0 \][/tex]
[tex]\[ z = -\frac{52}{3} \][/tex]

Question Help:
- Video 1
- Video 2
- Calculator


Sagot :

Certainly! Let's solve the system of equations using Cramer's Rule step-by-step. Our system of equations is:

[tex]\[ \left\{ \begin{array}{l} -2x + 4y - 9z = -32 \\ -3x + 5y - 9z = -30 \\ -x + 2y - 3z = -10 \end{array} \right. \][/tex]

### Step 1: Write down the coefficient matrix [tex]\( A \)[/tex]

The coefficient matrix [tex]\( A \)[/tex] is the matrix of the coefficients of [tex]\( x, y, \)[/tex] and [tex]\( z \)[/tex]:

[tex]\[ A = \begin{pmatrix} -2 & 4 & -9 \\ -3 & 5 & -9 \\ -1 & 2 & -3 \\ \end{pmatrix} \][/tex]

### Step 2: Calculate the determinant [tex]\( D \)[/tex] of matrix [tex]\( A \)[/tex]

To find [tex]\( D \)[/tex]:

[tex]\[ D = \det(A) \][/tex]

[tex]\[ D = \begin{vmatrix} -2 & 4 & -9 \\ -3 & 5 & -9 \\ -1 & 2 & -3 \end{vmatrix} \][/tex]

### Step 3: Write down the matrices [tex]\( D_x, D_y, \)[/tex] and [tex]\( D_z \)[/tex]

These matrices are formed by replacing one column of [tex]\( A \)[/tex] with the constants from the right-hand side of the equations (-32, -30, -10).

Matrix [tex]\( D_x \)[/tex]: replace the [tex]\( x \)[/tex]-column with the constants

[tex]\[ D_x = \begin{pmatrix} -32 & 4 & -9 \\ -30 & 5 & -9 \\ -10 & 2 & -3 \\ \end{pmatrix} \][/tex]

Matrix [tex]\( D_y \)[/tex]: replace the [tex]\( y \)[/tex]-column with the constants

[tex]\[ D_y = \begin{pmatrix} -2 & -32 & -9 \\ -3 & -30 & -9 \\ -1 & -10 & -3 \\ \end{pmatrix} \][/tex]

Matrix [tex]\( D_z \)[/tex]: replace the [tex]\( z \)[/tex]-column with the constants

[tex]\[ D_z = \begin{pmatrix} -2 & 4 & -32 \\ -3 & 5 & -30 \\ -1 & 2 & -10 \\ \end{pmatrix} \][/tex]

### Step 4: Calculate the determinants [tex]\( D_x, D_y, \)[/tex] and [tex]\( D_z \)[/tex]

To find [tex]\( D_x \)[/tex]:

[tex]\[ D_x = \det(D_x) \][/tex]

[tex]\[ D_x = \begin{vmatrix} -32 & 4 & -9 \\ -30 & 5 & -9 \\ -10 & 2 & -3 \end{vmatrix} \][/tex]

Similarly, we calculate:

[tex]\[ D_y = \det(D_y) \][/tex]

[tex]\[ D_y = \begin{vmatrix} -2 & -32 & -9 \\ -3 & -30 & -9 \\ -1 & -10 & -3 \end{vmatrix} \][/tex]

And finally:

[tex]\[ D_z = \det(D_z) \][/tex]

[tex]\[ D_z = \begin{vmatrix} -2 & 4 & -32 \\ -3 & 5 & -30 \\ -1 & 2 & -10 \end{vmatrix} \][/tex]

### Step 5: Solve for [tex]\( x, y, \)[/tex] and [tex]\( z \)[/tex] using Cramer's Rule

Cramer's Rule gives us the solution as:

[tex]\[ x = \frac{D_x}{D} \][/tex]

[tex]\[ y = \frac{D_y}{D} \][/tex]

[tex]\[ z = \frac{D_z}{D} \][/tex]

Substituting the known determinant values:

[tex]\[ D = 3.0000000000000018 \][/tex]

[tex]\[ D_x = -5.999999999999996 \][/tex]

[tex]\[ D_y = 0.0 \][/tex]

[tex]\[ D_z = 12.000000000000005 \][/tex]

Therefore,

[tex]\[ x = \frac{D_x}{D} = \frac{-5.999999999999996}{3.0000000000000018} = -2 \][/tex]

[tex]\[ y = \frac{D_y}{D} = \frac{0.0}{3.0000000000000018} = 0 \][/tex]

[tex]\[ z = \frac{D_z}{D} = \frac{12.000000000000005}{3.0000000000000018} = 4 \][/tex]

Thus, the solution to the system of equations is:

[tex]\[ \boxed{x = -2, \; y = 0, \; z = 4} \][/tex]