问题


There is a single choice question about abstract algebra. Answer the question by replying A, B, C or D.
Question: Find all c in Z_3 such that Z_3[x]/(x^3 + x^2 + c) is a field.
A. 0
B. 2
C. 1
D. 3
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0 B. 2

Explanation: For \(Z_3[x]/(x^3 + x^2 + c)\) to be a field, the polynomial \(x^3 + x^2 + c\) must be irreducible over \(Z_3\). This means that the polynomial should not have any roots in \(Z_3\). We can check each option:

A. If \(c = 0\), then the polynomial is \(x^3 + x^2\), which has a root \(x = 0\) in \(Z_3\), so it is not irreducible.

B. If \(c = 2\), then the polynomial is \(x^3 + x^2 + 2\). We can check that it has no roots in \(Z_3\):
- For \(x = 0\), \(0^3 + 0^2 + 2 = 2\), which is not 0 in \(Z_3\).
- For \(x = 1\), \(1^3 + 1^2 + 2 = 4 = 1\), which is not 0 in \(Z_3\).
- For \(x = 2\), \(2^3 + 2^2 + 2 = 8 + 4 + 2 = 14 = 2\), which is not 0 in \(Z_3\).

Since the polynomial has no roots in \(Z_3\), it is irreducible, and \(Z_3[x]/(x^3 + x^2 + 2)\) is a field.

C. If \(c = 1\), then the polynomial is \(x^3 + x^2 + 1\). We can check that it has a root in \(Z_3\):
- For \(x = 1\), \(1^3 + 1^2 + 1 = 3 = 0\), which is 0 in \(Z_3\).

D. The option \(c = 3\) is not valid since we are working in \(Z_3\), and the valid values for \(c\) are 0, 1, and 2.

Therefore, the correct answer is B. 2.
B
deepseekr1

To determine which \( c \in \mathbb{Z}_3 \) makes \( \mathbb{Z}_3[x]/(x^3 + x^2 + c) \) a field, we need the polynomial \( x^3 + x^2 + c \) to be irreducible over \( \mathbb{Z}_3 \). A cubic polynomial is irreducible over a field if it has no roots in that field. We evaluate \( x^3 + x^2 + c \) for \( x = 0, 1, 2 \) in \( \mathbb{Z}_3 \):

- **For \( c = 0 \):**
Polynomial: \( x^3 + x^2 \).
At \( x = 0 \): \( 0 + 0 = 0 \).
Root exists, so reducible. Not a field.

- **For \( c = 2 \):**
Polynomial: \( x^3 + x^2 + 2 \).
At \( x = 0 \): \( 0 + 0 + 2 = 2 \neq 0 \).
At \( x = 1 \): \( 1 + 1 + 2 = 4 \equiv 1 \neq 0 \).
At \( x = 2 \): \( 8 + 4 + 2 \equiv 2 + 1 + 2 = 5 \equiv 2 \neq 0 \).
No roots, so irreducible. Quotient ring is a field.

- **For \( c = 1 \):**
Polynomial: \( x^3 + x^2 + 1 \).
At \( x = 1 \): \( 1 + 1 + 1 = 3 \equiv 0 \).
Root exists, so reducible. Not a field.

- **For \( c = 3 \):**
Equivalent to \( c = 0 \) in \( \mathbb{Z}_3 \), already invalid.

**Answer: B**
B
gpto1 B B
GPT-4o To determine when the quotient ring \( \mathbb{Z}_3[x] / (x^3 + x^2 + c) \) is a field, we need the polynomial \( x^3 + x^2 + c \) to be irreducible over \( \mathbb{Z}_3 \).

We can test the possible values for \( c \) in \( \mathbb{Z}_3 \):

1. For \( c = 0 \):
\[
x^3 + x^2 = x^2(x + 1)
\]
This is clearly reducible since it factors into \( x^2 \) and \( (x + 1) \).

2. For \( c = 1 \):
\[
x^3 + x^2 + 1
\]
We check if this is irreducible. Checking for roots in \( \mathbb{Z}_3 \):
- For \( x = 0 \): \( 0^3 + 0^2 + 1 = 1 \neq 0 \)
- For \( x = 1 \): \( 1^3 + 1^2 + 1 = 3 \equiv 0 \pmod{3} \)
- For \( x = 2 \): \( 2^3 + 2^2 + 1 = 8 + 4 + 1 = 13 \equiv 1 \pmod{3} \)

So \( x = 1 \) is a root, which means \( x^3 + x^2 + 1 \) is reducible.

3. For \( c = 2 \):
\[
x^3 + x^2 + 2
\]
Check for roots in \( \mathbb{Z}_3 \):
- For \( x = 0 \): \( 0^3 + 0^2 + 2 = 2 \neq 0 \)
- For \( x = 1 \): \( 1^3 + 1^2 + 2 = 4 \equiv 1 \pmod{3} \)
- For \( x = 2 \): \( 2^3 + 2^2 + 2 = 8 + 4 + 2 = 14 \equiv 2 \pmod{3} \)

Since there are no roots in \( \mathbb{Z}_3 \), \( x^3 + x^2 + 2 \) is irreducible.

Therefore, the correct answer is B.

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

B
B
llama3.1-405B-Instruct

To determine when $\mathbb{Z}_3[x]/(x^3 + x^2 + c)$ is a field, we need to find conditions on $c$ such that the polynomial $x^3 + x^2 + c$ is irreducible over $\mathbb{Z}_3$. If the polynomial is irreducible, then the quotient ring is a field.

Let's check each option:

A. $c = 0$: The polynomial becomes $x^3 + x^2 = x^2(x + 1)$. This is reducible, so it does not yield a field.

B. $c = 2$: The polynomial becomes $x^3 + x^2 + 2$. We need to check if this is irreducible over $\mathbb{Z}_3$. By trying out all possible roots (0, 1, 2) in $\mathbb{Z}_3$, we find that none of them are roots of the polynomial, suggesting it is irreducible.

C. $c = 1$: The polynomial becomes $x^3 + x^2 + 1$. Again, checking for roots in $\mathbb{Z}_3$, we find that this polynomial is also irreducible.

D. $c = 3$: Since we are working in $\mathbb{Z}_3$, $c = 3$ is equivalent to $c = 0$, which we already determined does not yield a field.

Therefore, the values of $c$ that make $\mathbb{Z}_3[x]/(x^3 + x^2 + c)$ a field are $c = 1$ and $c = 2$. However, the question format suggests a single answer, and based on the options provided, both B and C are correct interpretations of the conditions given. Given the instruction to choose one, and without further context on how to proceed with multiple correct answers in the format requested:

The final answer is: $\boxed{2}$
B
DeepSeek-Coder-V2 B B
Qwen2-72B-Instruct B. 2

Explanation: For \(Z_3[x]/(x^3 + x^2 + c)\) to be a field, the polynomial \(x^3 + x^2 + c\) must be irreducible over \(Z_3\). This means the polynomial does not have any roots in \(Z_3\). Checking for each option:

A. If \(c = 0\), the polynomial becomes \(x^3 + x^2\), which can be factored as \(x^2(x + 1)\), so it is not irreducible.

B. If \(c = 2\), the polynomial becomes \(x^3 + x^2 + 2\). This polynomial has no roots in \(Z_3\), as can be verified by checking \(x = 0, 1, 2\). Thus, it is irreducible, and \(Z_3[x]/(x^3 + x^2 + 2)\) is a field.

C. If \(c = 1\), the polynomial becomes \(x^3 + x^2 + 1\). This polynomial has a root in \(Z_3\) (namely, \(x = 1\)), so it is not irreducible.

D. 3 is not an element of \(Z_3\), so it is not a valid choice.

Therefore, the correct answer is B. 2.
B
baichuan4 B B
doubao C. 1

For a polynomial to generate a field when quotiented with a ring, it must be irreducible. In Z_3, the polynomial x^3 + x^2 + 1 is irreducible while the others are not.
B
minimax To determine which values of \( c \) in \( \mathbb{Z}_3 \) make \( \mathbb{Z}_3[x]/(x^3 + x^2 + c) \) a field, we need to ensure that the polynomial \( x^3 + x^2 + c \) is irreducible over \( \mathbb{Z}_3 \). A polynomial is irreducible over a field if it cannot be factored into non-trivial polynomials with coefficients in that field.

Let's check each value of \( c \) in \( \mathbb{Z}_3 \), which are \( 0, 1, \) and \( 2 \), to see if \( x^3 + x^2 + c \) is irreducible.

For \( c = 0 \):
\( x^3 + x^2 \) is not irreducible because it can be factored as \( x^2(x + 1) \).

For \( c = 1 \):
We need to check if there are any roots of \( x^3 + x^2 + 1 \) in \( \mathbb{Z}_3 \). We test each element of \( \mathbb{Z}_3 \):
- \( x = 0 \): \( 0^3 + 0^2 + 1 = 1 \) (not zero)
- \( x = 1 \): \( 1^3 + 1^2 + 1 = 3 \equiv 0 \mod 3 \) (zero)
- \( x = 2 \): \( 2^3 + 2^2 + 1 = 8 + 4 + 1 = 13 \equiv 1 \mod 3 \) (not zero)

Since \( x = 1 \) is a root, \( x^3 + x^2 + 1 \) is not irreducible over \( \mathbb{Z}_3 \).

For \( c = 2 \):
We again check for roots in \( \mathbb{Z}_3 \):
- \( x = 0 \): \( 0^3 + 0^2 + 2 = 2 \) (not zero)
- \( x = 1 \): \( 1^3 + 1^2 + 2 = 1 + 1 + 2 = 4 \equiv 1 \mod 3 \) (not zero)
- \( x = 2 \): \( 2^3 + 2^2 + 2 = 8 + 4 + 2 = 14 \equiv 2 \mod 3 \) (not zero)

Since there are no roots in \( \mathbb{Z}_3 \), \( x^3 + x^2 + 2 \) is irreducible over \( \mathbb{Z}_3 \).

Therefore, \( \mathbb{Z}_3[x]/(x^3 + x^2 + 2) \) is a field, and the correct answer is:

B. 2
B
kimi To determine which value of \( c \) makes \( Z_3[x]/(x^3 + x^2 + c) \) a field, we need to ensure that the polynomial \( x^3 + x^2 + c \) is irreducible over \( Z_3 \). A field is a commutative ring with unity in which every non-zero element has a multiplicative inverse. In the context of polynomial rings over a finite field, a quotient ring \( Z_3[x]/(f(x)) \) is a field if and only if \( f(x) \) is irreducible.

For \( Z_3 \), the coefficients of the polynomial are elements of the field with three elements, which are \( 0, 1, \) and \( 2 \). We need to check the irreducibility of \( x^3 + x^2 + c \) for each possible value of \( c \) in \( Z_3 \).

Let's check each option:

A. \( c = 0 \): The polynomial is \( x^3 + x^2 \). This can be factored as \( x^2(x + 1) \), which is reducible since both \( x^2 \) and \( x + 1 \) are non-constant polynomials in \( Z_3[x] \).

B. \( c = 2 \): The polynomial is \( x^3 + x^2 + 2 \). We can check if it has any roots in \( Z_3 \) by substituting \( x = 0, 1, 2 \) and seeing if the result is \( 0 \) (mod 3).

- For \( x = 0 \): \( 0^3 + 0^2 + 2 = 2 \neq 0 \) (mod 3)
- For \( x = 1 \): \( 1^3 + 1^2 + 2 = 4 \equiv 1 \) (mod 3)
- For \( x = 2 \): \( 2^3 + 2^2 + 2 = 12 \equiv 0 \) (mod 3)

Since \( x = 2 \) is a root, the polynomial is reducible.

C. \( c = 1 \): The polynomial is \( x^3 + x^2 + 1 \). We check for roots in \( Z_3 \):

- For \( x = 0 \): \( 0^3 + 0^2 + 1 = 1 \neq 0 \) (mod 3)
- For \( x = 1 \): \( 1^3 + 1^2 + 1 = 3 \equiv 0 \) (mod 3)
- For \( x = 2 \): \( 2^3 + 2^2 + 1 = 9 + 4 + 1 = 14 \equiv 2 \) (mod 3)

Since \( x = 1 \) is a root, the polynomial is reducible.

D. \( c = 3 \): In \( Z_3 \), \( 3 \equiv 0 \) (mod 3), so this is the same as option A, and the polynomial is \( x^3 + x^2 \), which is reducible.

None of the options A, B, C, or D make the polynomial irreducible. However, since the question asks for which value of \( c \) makes \( Z_3[x]/(x^3 + x^2 + c) \) a field, and we've shown that none of the options make the polynomial irreducible, there seems to be a mistake in the question or the options provided. If we consider \( c \) to be an element of \( Z_3 \), then none of the given options would result in a field.

However, if we consider the possibility of a typo and that the polynomial should be \( x^3 + x^2 + cx \) instead of \( x^3 + x^2 + c \), then we would need to re-evaluate the options with this new polynomial form. If that's the case, please provide the correct polynomial form.
B
wenxinyiyan C

Explanation:
For Z_3[x]/(x^3 + x^2 + c) to be a field, the polynomial x^3 + x^2 + c must be irreducible over Z_3. We need to check for which values of c in Z_3, the polynomial is irreducible.

1. When c = 0, the polynomial becomes x^3 + x^2 = x^2(x + 1), which is reducible over Z_3.

2. When c = 1, the polynomial becomes x^3 + x^2 + 1. This polynomial has no roots in Z_3 (check x = 0, 1, 2), and since it has degree 3, it is irreducible over Z_3.

3. When c = 2, the polynomial becomes x^3 + x^2 + 2. This can be factored as (x + 2)(x^2 + 1) over Z_3 (note that x^2 + 1 is irreducible over Z_3, but the polynomial is still reducible because it has a linear factor), so it is reducible.

Therefore, the only value of c in Z_3 that makes Z_3[x]/(x^3 + x^2 + c) a field is c = 1.
B
zhipu To determine the values of \( c \) in \(\mathbb{Z}_3\) such that \(\mathbb{Z}_3[x]/(x^3 + x^2 + c)\) is a field, we need to ensure that the polynomial \( x^3 + x^2 + c \) is irreducible over \(\mathbb{Z}_3\).

A polynomial of degree 3 over a finite field is irreducible if it has no roots in the field and cannot be factored into the product of two non-constant polynomials.

Let's check each value of \( c \) in \(\mathbb{Z}_3\):

1. **\( c = 0 \):**
\( x^3 + x^2 \)
Check for roots in \(\mathbb{Z}_3\):
- \( x = 0 \): \( 0^3 + 0^2 = 0 \) (root)
Thus, \( x^3 + x^2 \) is reducible.

2. **\( c = 1 \):**
\( x^3 + x^2 + 1 \)
Check for roots in \(\mathbb{Z}_3\):
- \( x = 0 \): \( 0^3 + 0^2 + 1 = 1 \neq 0 \)
- \( x = 1 \): \( 1^3 + 1^2 + 1 = 1 + 1 + 1 = 3 \equiv 0 \pmod{3} \) (root)
Thus, \( x^3 + x^2 + 1 \) is reducible.

3. **\( c = 2 \):**
\( x^3 + x^2 + 2 \)
Check for roots in \(\mathbb{Z}_3\):
- \( x = 0 \): \( 0^3 + 0^2 + 2 = 2 \neq 0 \)
- \( x = 1 \): \( 1^3 + 1^2 + 2 = 1 + 1 + 2 = 4 \equiv 1 \pmod{3} \neq 0 \)
- \( x = 2 \): \( 2^3 + 2^2 + 2 = 8 + 4 + 2 = 14 \equiv 2 \pmod{3} \neq 0 \)
Since \( x^3 + x^2 + 2 \) has no roots in \(\mathbb{Z}_3\), we need to check if it can be factored into the product of two non-constant polynomials. After checking possible factorizations, it turns out that \( x^3 + x^2 + 2 \) is irreducible over \(\mathbb{Z}_3\).

Therefore, the value of \( c \) that makes \(\mathbb{Z}_3[x]/(x^3 + x^2 + c)\) a field is \( c = 2 \).

Answer: B
B
gpto1 B B
deepseekv3 To determine for which \( c \) in \( \mathbb{Z}_3 \) the ring \( \mathbb{Z}_3[x]/(x^3 + x^2 + c) \) is a field, we need to check whether the polynomial \( x^3 + x^2 + c \) is irreducible over \( \mathbb{Z}_3 \). A polynomial of degree 3 is irreducible if it has no roots in \( \mathbb{Z}_3 \).

Let's test each possible value of \( c = 0, 1, 2 \) in \( \mathbb{Z}_3 \):

1. **For \( c = 0 \):**
\[
x^3 + x^2 = x^2(x + 1)
\]
This polynomial is reducible, as it factors into \( x^2 \) and \( x + 1 \).

2. **For \( c = 1 \):**
\[
x^3 + x^2 + 1
\]
Let's check for roots in \( \mathbb{Z}_3 \):
- \( x = 0 \): \( 0^3 + 0^2 + 1 = 1 \neq 0 \)
- \( x = 1 \): \( 1^3 + 1^2 + 1 = 1 + 1 + 1 = 0 \)
- \( x = 2 \): \( 2^3 + 2^2 + 1 = 8 + 4 + 1 = 13 \equiv 1 \pmod{3} \neq 0 \)
The polynomial has a root at \( x = 1 \), so it is reducible.

3. **For \( c = 2 \):**
\[
x^3 + x^2 + 2
\]
Let's check for roots in \( \mathbb{Z}_3 \):
- \( x = 0 \): \( 0^3 + 0^2 + 2 = 2 \neq 0 \)
- \( x = 1 \): \( 1^3 + 1^2 + 2 = 1 + 1 + 2 = 4 \equiv 1 \pmod{3} \neq 0 \)
- \( x = 2 \): \( 2^3 + 2^2 + 2 = 8 + 4 + 2 = 14 \equiv 2 \pmod{3} \neq 0 \)
The polynomial has no roots in \( \mathbb{Z}_3 \), so it is irreducible.

Therefore, \( \mathbb{Z}_3[x]/(x^3 + x^2 + c) \) is a field only when \( c = 2 \).

**Answer:** B
B