问题


There is a single choice question about college mathematics. Answer the question by replying A, B, C or D.
Question: If A is the 2 by 2 matrix whose (i, j) entry is equal to i + j, and B is the 3 by 3 matrix whose (i, j) entry is equal to i + j, find the value of the sum detA + detB.
A. -2
B. -1
C. 0
D. 2
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

C
B
deepseekr1

To determine the value of detA + detB, we first construct matrices A and B based on their entries defined by \(i + j\).

**Matrix A (2x2):**
\[
A = \begin{bmatrix}
1+1 & 1+2 \\
2+1 & 2+2
\end{bmatrix}
= \begin{bmatrix}
2 & 3 \\
3 & 4
\end{bmatrix}
\]
The determinant of A is:
\[
\det(A) = (2)(4) - (3)(3) = 8 - 9 = -1.
\]

**Matrix B (3x3):**
\[
B = \begin{bmatrix}
1+1 & 1+2 & 1+3 \\
2+1 & 2+2 & 2+3 \\
3+1 & 3+2 & 3+3
\end{bmatrix}
= \begin{bmatrix}
2 & 3 & 4 \\
3 & 4 & 5 \\
4 & 5 & 6
\end{bmatrix}
\]
To compute \(\det(B)\), we perform row operations. Subtracting the first row from the second and third rows:
\[
\text{Row2'} = \text{Row2} - \text{Row1} = [1, 1, 1], \quad
\text{Row3'} = \text{Row3} - \text{Row1} = [2, 2, 2].
\]
The modified matrix becomes:
\[
\begin{bmatrix}
2 & 3 & 4 \\
1 & 1 & 1 \\
2 & 2 & 2
\end{bmatrix}.
\]
Since Row3' is twice Row2', the rows are linearly dependent, so \(\det(B) = 0\).

**Sum of determinants:**
\[
\det(A) + \det(B) = -1 + 0 = -1.
\]

**Answer: B.**
B
gpto1 B B
GPT-4o To determine the value of \(\text{det}A + \text{det}B\), we need to find the determinants of the matrices \(A\) and \(B\).

First, let's find matrix \(A\):
\[ A = \begin{pmatrix}
1+1 & 1+2 \\
2+1 & 2+2
\end{pmatrix}
= \begin{pmatrix}
2 & 3 \\
3 & 4
\end{pmatrix} \]

Now, we calculate the determinant of \(A\):
\[ \text{det}A = (2 \times 4) - (3 \times 3) = 8 - 9 = -1 \]

Next, let's find matrix \(B\):
\[ B = \begin{pmatrix}
1+1 & 1+2 & 1+3 \\
2+1 & 2+2 & 2+3 \\
3+1 & 3+2 & 3+3
\end{pmatrix}
= \begin{pmatrix}
2 & 3 & 4 \\
3 & 4 & 5 \\
4 & 5 & 6
\end{pmatrix} \]

Now, we calculate the determinant of \(B\). Notice that each row of \(B\) can be written as a linear combination of other rows (e.g., Row 3 = Row 1 + 2). This means that the rows of \(B\) are linearly dependent and hence \(\text{det}B = 0\).

Finally, sum the determinants:
\[ \text{det}A + \text{det}B = -1 + 0 = -1 \]

Thus, the value of \(\text{det}A + \text{det}B\) is \(\boxed{-1}\).

Answer: B
B
llama3.1-70B-Instruct

A
B
llama3.1-405B-Instruct

A = \begin{bmatrix} 2 & 3 \\ 3 & 4 \end{bmatrix} and B = \begin{bmatrix} 2 & 3 & 4 \\ 3 & 4 & 5 \\ 4 & 5 & 6 \end{bmatrix}
detA = 2(4) - 3(3) = -1
detB = 2(4(6) - 5(5)) - 3(3(6) - 5(4)) + 4(3(5) - 4(4)) = 2(24 - 25) - 3(18 - 20) + 4(15 - 16) = -2 + 6 - 4 = 0
detA + detB = -1 + 0 = -1
The best answer is B.
B
DeepSeek-Coder-V2 C. 0 B
Qwen2-72B-Instruct C. 0 B
baichuan4 To find the determinant of a 2x2 matrix [[a, b], [c, d]], we use the formula ad - bc.

For matrix A, the entries are:
a = 1+1 = 2
b = 1+2 = 3
c = 2+1 = 3
d = 2+2 = 4

So, det(A) = (2)(4) - (3)(3) = 8 - 9 = -1.

To find the determinant of a 3x3 matrix [[a, b, c], [d, e, f], [g, h, i]], we use the formula aei + bfg + cdh - ceg - bdi - afh.

For matrix B, the entries are:
a = 1+1 = 2
b = 1+2 = 3
c = 1+3 = 4
d = 2+1 = 3
e = 2+2 = 4
f = 2+3 = 5
g = 3+1 = 4
h = 3+2 = 5
i = 3+3 = 6

So, det(B) = (2)(4)(6) + (3)(5)(4) + (4)(3)(5) - (4)(4)(3) - (3)(3)(6) - (2)(5)(5) = 48 + 60 + 60 - 48 - 54 - 50 = 0.

Therefore, det(A) + det(B) = -1 + 0 = -1.

Answer: B. -1
B
doubao The matrix A is [[1, 2], [2, 3]]. The determinant of A is 1*3 - 2*2 = -1.

The matrix B is [[1, 2, 3], [2, 3, 4], [3, 4, 5]]. The determinant of B is 0.

So detA + detB = -1 + 0 = -1.

The answer is B.
B
minimax Let's calculate the determinants of matrices A and B.

Matrix A is a 2x2 matrix with entries given by:
\[ A = \begin{bmatrix} 1+1 & 1+2 \\ 2+1 & 2+2 \end{bmatrix} = \begin{bmatrix} 2 & 3 \\ 3 & 4 \end{bmatrix} \]

The determinant of A, denoted as det(A), is calculated as:
\[ \text{det}(A) = (2)(4) - (3)(3) = 8 - 9 = -1 \]

Matrix B is a 3x3 matrix with entries given by:
\[ B = \begin{bmatrix} 1+1 & 1+2 & 1+3 \\ 2+1 & 2+2 & 2+3 \\ 3+1 & 3+2 & 3+3 \end{bmatrix} = \begin{bmatrix} 2 & 3 & 4 \\ 3 & 4 & 5 \\ 4 & 5 & 6 \end{bmatrix} \]

The determinant of B, denoted as det(B), can be calculated using the rule of Sarrus or the general formula for 3x3 matrices:
\[ \text{det}(B) = 2(4\cdot6 - 5\cdot5) - 3(3\cdot6 - 5\cdot4) + 4(3\cdot5 - 4\cdot4) \]
\[ \text{det}(B) = 2(24 - 25) - 3(18 - 20) + 4(15 - 16) \]
\[ \text{det}(B) = 2(-1) - 3(-2) + 4(-1) \]
\[ \text{det}(B) = -2 + 6 - 4 \]
\[ \text{det}(B) = 0 \]

Now, we add the determinants of A and B:
\[ \text{det}(A) + \text{det}(B) = -1 + 0 = -1 \]

The answer is B. -1.
B
kimi To solve this problem, we need to find the determinants of matrices A and B and then sum them up.

Matrix A is a 2x2 matrix where the entry in the i-th row and j-th column is i + j. So, matrix A looks like this:

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

The determinant of a 2x2 matrix is calculated as follows:

\[
\text{det}(A) = ad - bc
\]

For matrix A:

\[
\text{det}(A) = (2)(4) - (3)(3) = 8 - 9 = -1
\]

Matrix B is a 3x3 matrix where the entry in the i-th row and j-th column is i + j. So, matrix B looks like this:

\[
B = \begin{bmatrix}
1+1 & 1+2 & 1+3 \\
2+1 & 2+2 & 2+3 \\
3+1 & 3+2 & 3+3
\end{bmatrix}
= \begin{bmatrix}
2 & 3 & 4 \\
3 & 4 & 5 \\
4 & 5 & 6
\end{bmatrix}
\]

The determinant of a 3x3 matrix is calculated as follows:

\[
\text{det}(B) = aei + bfg + cdh - ceg - bdi - afh
\]

For matrix B:

\[
\text{det}(B) = (2)(4)(6) + (3)(5)(4) + (4)(3)(5) - (4)(5)(4) - (3)(4)(6) - (2)(3)(5)
\]
\[
\text{det}(B) = 48 + 60 + 60 - 80 - 72 - 30 = 128 - 182 = -54
\]

Now, we sum the determinants of A and B:

\[
\text{det}(A) + \text{det}(B) = -1 + (-54) = -55
\]

However, none of the options match -55. There might be a mistake in the calculation or the options provided. Let's double-check the calculation for matrix B.

\[
\text{det}(B) = (2)(4)(6) + (3)(5)(4) + (4)(3)(5) - (4)(5)(4) - (3)(4)(6) - (2)(3)(5)
\]
\[
\text{det}(B) = 48 + 60 + 60 - 80 - 72 - 30 = -54
\]

The calculation for matrix B is correct, but the result does not match any of the given options. If we assume the options are correct, then there might be an error in the problem statement or the options provided. If we strictly follow the options given, none of them is correct based on the calculations above.
B
wenxinyiyan D

Explanation:
Matrix A is a 2x2 matrix with entries:
A = $\begin{bmatrix} 1+1 & 1+2 \\ 2+1 & 2+2 \end{bmatrix}$ = $\begin{bmatrix} 2 & 3 \\ 3 & 4 \end{bmatrix}$

The determinant of A, detA, is given by:
detA = (2*4) - (3*3) = 8 - 9 = -1

Matrix B is a 3x3 matrix with entries:
B = $\begin{bmatrix} 1+1 & 1+2 & 1+3 \\ 2+1 & 2+2 & 2+3 \\ 3+1 & 3+2 & 3+3 \end{bmatrix}$ = $\begin{bmatrix} 2 & 3 & 4 \\ 3 & 4 & 5 \\ 4 & 5 & 6 \end{bmatrix}$

To find the determinant of B, detB, we can use the cofactor expansion method along any row or column. Let's expand along the first row:
detB = 2*$\begin{vmatrix} 4 & 5 \\ 5 & 6 \end{vmatrix}$ - 3*$\begin{vmatrix} 3 & 5 \\ 4 & 6 \end{vmatrix}$ + 4*$\begin{vmatrix} 3 & 4 \\ 4 & 5 \end{vmatrix}$
= 2*(24-25) - 3*(18-20) + 4*(15-16)
= 2*(-1) - 3*(-2) + 4*(-1)
= -2 + 6 - 4
= 0

Finally, the sum detA + detB is:
detA + detB = -1 + 0 = -1

However, upon closer inspection, we notice that matrix B has two rows (the second and third) that are linearly dependent (one row is a constant multiple of the other). This means that detB must be zero, as the determinant of a matrix with linearly dependent rows (or columns) is always zero.

Since our calculation of detB also yielded 0, we confirm that detB is indeed 0.

Now, the corrected sum is:
detA + detB = -1 + 0 = -1 (if we consider only the numerical calculation)

But since the question asks for the value of the sum and we know that detB is zero due to linear dependency, the sum is actually:
detA + detB = -1 + 0 = 0 (if we consider the conceptual understanding)

However, there seems to be a discrepancy in the solutions provided. If we strictly follow the numerical calculations, the answer would be -1, but if we take into account the linear dependency of matrix B, the answer would be 0.

Given that the options are -2, -1, 0, and 2, and considering the linear dependency of matrix B which makes detB = 0, the most appropriate answer would be:

C. 0

Note: The initial calculation of detB was included to show the process, but the key point is that detB is zero due to linear dependency, making the final answer 0.
B
zhipu To answer this question, we first need to determine the matrices \( A \) and \( B \), then calculate their determinants.

### Matrix \( A \)
Matrix \( A \) is a 2x2 matrix where the (i, j) entry is \( i + j \).

So, for a 2x2 matrix:
- The (1, 1) entry is \( 1 + 1 = 2 \)
- The (1, 2) entry is \( 1 + 2 = 3 \)
- The (2, 1) entry is \( 2 + 1 = 3 \)
- The (2, 2) entry is \( 2 + 2 = 4 \)

Thus, matrix \( A \) is:
\[ A = \begin{pmatrix}
2 & 3 \\
3 & 4
\end{pmatrix} \]

The determinant of a 2x2 matrix \( \begin{pmatrix} a & b \\ c & d \end{pmatrix} \) is given by \( ad - bc \).

So, for matrix \( A \):
\[ \text{det}(A) = 2 \cdot 4 - 3 \cdot 3 = 8 - 9 = -1 \]

### Matrix \( B \)
Matrix \( B \) is a 3x3 matrix where the (i, j) entry is \( i + j \).

So, for a 3x3 matrix:
- The (1, 1) entry is \( 1 + 1 = 2 \)
- The (1, 2) entry is \( 1 + 2 = 3 \)
- The (1, 3) entry is \( 1 + 3 = 4 \)
- The (2, 1) entry is \( 2 + 1 = 3 \)
- The (2, 2) entry is \( 2 + 2 = 4 \)
- The (2, 3) entry is \( 2 + 3 = 5 \)
- The (3, 1) entry is \( 3 + 1 = 4 \)
- The (3, 2) entry is \( 3 + 2 = 5 \)
- The (3, 3) entry is \( 3 + 3 = 6 \)

Thus, matrix \( B \) is:
\[ B = \begin{pmatrix}
2 & 3 & 4 \\
3 & 4 & 5 \\
4 & 5 & 6
\end{pmatrix} \]

The determinant of a 3x3 matrix \( \begin{pmatrix} a & b & c \\ d & e & f \\ g & h & i \end{pmatrix} \) is given by:
\[ \text{det}(B) = a(ei - fh) - b(di - fg) + c(dh - eg) \]

Substituting the values from matrix \( B \):
\[ \text{det}(B) = 2(4 \cdot 6 - 5 \cdot 5) - 3(3 \cdot 6 - 5 \cdot 4) + 4(3 \cdot 5 - 4 \cdot 4) \]
\[ = 2(24 - 25) - 3(18 - 20) + 4(15 - 16) \]
\[ = 2(-1) - 3(-2) + 4(-1) \]
\[ = -2 + 6 - 4 \]
\[ = 0 \]

### Sum of Determinants
Now, we find the sum \( \text{det}(A) + \text{det}(B) \):
\[ \text{det}(A) + \text{det}(B) = -1 + 0 = -1 \]

Therefore, the value of the sum \( \text{det}(A) + \text{det}(B) \) is \( -1 \).

**Answer: B**
B
gpto1 B B
deepseekv3 To solve the problem, we first construct the matrices \( A \) and \( B \) based on the given conditions, then compute their determinants, and finally find the sum of these determinants.

### Step 1: Construct Matrix \( A \)
Matrix \( A \) is a \( 2 \times 2 \) matrix where each entry \( a_{i,j} \) is equal to \( i + j \).

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

### Step 2: Compute det\( A \)
The determinant of a \( 2 \times 2 \) matrix \( \begin{bmatrix} a & b \\ c & d \end{bmatrix} \) is calculated as \( ad - bc \).

\[
\det A = (2)(4) - (3)(3) = 8 - 9 = -1
\]

### Step 3: Construct Matrix \( B \)
Matrix \( B \) is a \( 3 \times 3 \) matrix where each entry \( b_{i,j} \) is equal to \( i + j \).

\[
B = \begin{bmatrix}
1+1 & 1+2 & 1+3 \\
2+1 & 2+2 & 2+3 \\
3+1 & 3+2 & 3+3
\end{bmatrix}
= \begin{bmatrix}
2 & 3 & 4 \\
3 & 4 & 5 \\
4 & 5 & 6
\end{bmatrix}
\]

### Step 4: Compute det\( B \)
The determinant of a \( 3 \times 3 \) matrix can be calculated using the rule of Sarrus or cofactor expansion. Here, we use cofactor expansion along the first row.

\[
\det B = 2 \cdot \det \begin{bmatrix} 4 & 5 \\ 5 & 6 \end{bmatrix} - 3 \cdot \det \begin{bmatrix} 3 & 5 \\ 4 & 6 \end{bmatrix} + 4 \cdot \det \begin{bmatrix} 3 & 4 \\ 4 & 5 \end{bmatrix}
\]

Calculating the minors:

\[
\det \begin{bmatrix} 4 & 5 \\ 5 & 6 \end{bmatrix} = (4)(6) - (5)(5) = 24 - 25 = -1
\]
\[
\det \begin{bmatrix} 3 & 5 \\ 4 & 6 \end{bmatrix} = (3)(6) - (5)(4) = 18 - 20 = -2
\]
\[
\det \begin{bmatrix} 3 & 4 \\ 4 & 5 \end{bmatrix} = (3)(5) - (4)(4) = 15 - 16 = -1
\]

Substituting back:

\[
\det B = 2(-1) - 3(-2) + 4(-1) = -2 + 6 - 4 = 0
\]

### Step 5: Compute det\( A \) + det\( B \)
\[
\det A + \det B = -1 + 0 = -1
\]

Therefore, the correct answer is:

**B. -1**
B