1. **Problem Statement:**
Evaluate the following matrix expressions and find the values of variables $x$, $y$, and $z$ given matrices $M$, $A$, and $B$.
2. **Given Matrices:**
$$M = \begin{pmatrix} 1 & 2 & x^3 \\ 4 & 1 & 0 \\ 7 & x+3 & 8 \end{pmatrix}, \quad M^t = \begin{pmatrix} 1 & 4 & 7 \\ 2 & 1 & x+3 \\ x^3 & 0 & 8 \end{pmatrix}$$
$$A = \begin{pmatrix} x+1 & -3 \\ y+7 & 3y+4 \end{pmatrix}, \quad B = \begin{pmatrix} 2x-6 & -3 \\ 1 & 1 \end{pmatrix}$$
3. **Step 1: Find $x$ from $M$ and $M^t$**
By definition, the transpose $M^t$ swaps rows and columns of $M$.
Check element $(2,3)$ in $M$ and element $(3,2)$ in $M^t$:
$$M_{2,3} = 0, \quad M^t_{3,2} = 0$$
Check element $(3,2)$ in $M$ and element $(2,3)$ in $M^t$:
$$M_{3,2} = x+3, \quad M^t_{2,3} = x+3$$
These match, so no new info here.
Check element $(1,3)$ in $M$ and element $(3,1)$ in $M^t$:
$$M_{1,3} = x^3, \quad M^t_{3,1} = x^3$$
These match.
No contradictions, so $x$ remains a variable here.
4. **Step 2: Find $x$, $y$, and $z$ from $A$, $B$, and $P=B$**
Given $P = B$, and matrices $A$ and $B$ as above.
5. **Step 3: Find $x$ and $y$ by equating $A$ and $B$ if needed**
Since $P = B$, and no direct equation for $A = P$ is given, we assume to find $x$ and $y$ such that $A = B$ or use other conditions.
6. **Step 4: Solve for $x$ and $y$ by equating corresponding elements of $A$ and $B$**
Equate $A_{1,1}$ and $B_{1,1}$:
$$x + 1 = 2x - 6$$
Rearranged:
$$x + 1 = 2x - 6 \implies 1 + 6 = 2x - x \implies 7 = x$$
7. **Step 5: Solve for $y$ by equating $A_{2,1}$ and $B_{2,1}$**
$$y + 7 = 1 \implies y = 1 - 7 = -6$$
8. **Step 6: Solve for $y$ by equating $A_{2,2}$ and $B_{2,2}$**
$$3y + 4 = 1 \implies 3y = 1 - 4 = -3 \implies y = -1$$
Conflict arises: $y = -6$ from one element and $y = -1$ from another.
This means $A \neq B$ generally.
9. **Step 7: Since $P = B$ is given, and no $z$ in $A$ or $B$, $z$ is undefined here.**
10. **Step 8: Calculate $A^t$ (transpose of $A$) with $x=7$ and $y=-6$ (choosing $y=-6$ from step 5):**
$$A = \begin{pmatrix} 7+1 & -3 \\ -6+7 & 3(-6)+4 \end{pmatrix} = \begin{pmatrix} 8 & -3 \\ 1 & -14 \end{pmatrix}$$
Transpose:
$$A^t = \begin{pmatrix} 8 & 1 \\ -3 & -14 \end{pmatrix}$$
11. **Summary of answers:**
- $x = 7$
- $y = -6$ (chosen for consistency)
- $z$ not defined in given matrices
- $A = \begin{pmatrix} 8 & -3 \\ 1 & -14 \end{pmatrix}$
- $A^t = \begin{pmatrix} 8 & 1 \\ -3 & -14 \end{pmatrix}$
"slug":"matrix variables",
"subject":"algebra",
"desmos":{ "latex":"", "features":{} },
"q_count":2
Matrix Variables E20D89
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.