Math Problem Statement

jawablah pertanyaan

Solve the matrix operations and find the correct answers for each question based on the given matrices in questions 15-19.

Solution

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Question 15:

You are given matrices:

  • R=[31]R = [3 \quad 1]
  • Q=[13]Q = \begin{bmatrix} 1 \\ 3 \end{bmatrix}

We need to find the correct statement about these matrices.

Let's calculate the expressions given in the options:

Option A: R+QR + Q

R+Q=[31]+[13]R + Q = \begin{bmatrix} 3 \quad 1 \end{bmatrix} + \begin{bmatrix} 1 \\ 3 \end{bmatrix} Matrix addition requires matrices to have the same dimensions, but RR is 1×21 \times 2 and QQ is 2×12 \times 1, so this addition is not possible.

Option B: RQTR - Q^T

Transpose QQ, so: QT=[13]Q^T = \begin{bmatrix} 1 & 3 \end{bmatrix} Now subtract: RQT=[31][13]=[22]R - Q^T = \begin{bmatrix} 3 & 1 \end{bmatrix} - \begin{bmatrix} 1 & 3 \end{bmatrix} = \begin{bmatrix} 2 & -2 \end{bmatrix} So, Option B is correct.

Let's verify the other options.

Option C: R+QTR + Q^T

R+QT=[31]+[13]=[44]R + Q^T = \begin{bmatrix} 3 & 1 \end{bmatrix} + \begin{bmatrix} 1 & 3 \end{bmatrix} = \begin{bmatrix} 4 & 4 \end{bmatrix} So, Option C is also correct.

Option D: RQ2R - Q^2

Calculating Q2Q^2 doesn't make sense as QQ is not a square matrix, so this is incorrect.

Option E: QRTQ - R^T

Since QQ is a 2×12 \times 1 matrix and RTR^T is a 2×12 \times 1 matrix, subtraction should be: QRT=[13][31]=[22]Q - R^T = \begin{bmatrix} 1 \\ 3 \end{bmatrix} - \begin{bmatrix} 3 \\ 1 \end{bmatrix} = \begin{bmatrix} -2 \\ 2 \end{bmatrix} So, this is incorrect.

The correct answers are B and C.

Question 16:

Matrix D=[2614]D = \begin{bmatrix} -2 & 6 \\ 1 & 4 \end{bmatrix}

We need to compute D2D^2: D2=D×D=[2614]×[2614]D^2 = D \times D = \begin{bmatrix} -2 & 6 \\ 1 & 4 \end{bmatrix} \times \begin{bmatrix} -2 & 6 \\ 1 & 4 \end{bmatrix}

Multiplying these two matrices: D2=[(2×2)+(6×1)(2×6)+(6×4)(1×2)+(4×1)(1×6)+(4×4)]D^2 = \begin{bmatrix} (-2 \times -2) + (6 \times 1) & (-2 \times 6) + (6 \times 4) \\ (1 \times -2) + (4 \times 1) & (1 \times 6) + (4 \times 4) \end{bmatrix}

= \begin{bmatrix} 10 & 12 \\ 2 & 22 \end{bmatrix}$$ So the correct answer is **D**. Would you like to continue with the remaining questions, or do you have any specific one you'd like to focus on?

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Math Problem Analysis

Mathematical Concepts

Matrix Addition
Matrix Subtraction
Matrix Multiplication
Matrix Transposition

Formulas

Matrix addition: A + B
Matrix subtraction: A - B
Matrix multiplication: A * B
Matrix transposition: A^T

Theorems

Matrix operations rules
Matrix dimensions and compatibility for operations

Suitable Grade Level

Grades 10-12