Question about ring homomorphism.
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I have a ring homomorphism $f : mathbbZ[x] to mathbbZ$ such that $f$ sends $x$ to $3$. I want to find $f(x^3+2)$.
My attempt is, since $f$ is a homomorphism
$$f(x^3+2)=f^3(x)+f(2)=27+f(2)$$ but what is $f(2)$?
abstract-algebra
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up vote
4
down vote
favorite
I have a ring homomorphism $f : mathbbZ[x] to mathbbZ$ such that $f$ sends $x$ to $3$. I want to find $f(x^3+2)$.
My attempt is, since $f$ is a homomorphism
$$f(x^3+2)=f^3(x)+f(2)=27+f(2)$$ but what is $f(2)$?
abstract-algebra
3
A ring homomorphism sends the identity to the identity, hence $f(1)=1$, so $f(2)=f(1+1)=,...$
– quasi
4 hours ago
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up vote
4
down vote
favorite
up vote
4
down vote
favorite
I have a ring homomorphism $f : mathbbZ[x] to mathbbZ$ such that $f$ sends $x$ to $3$. I want to find $f(x^3+2)$.
My attempt is, since $f$ is a homomorphism
$$f(x^3+2)=f^3(x)+f(2)=27+f(2)$$ but what is $f(2)$?
abstract-algebra
I have a ring homomorphism $f : mathbbZ[x] to mathbbZ$ such that $f$ sends $x$ to $3$. I want to find $f(x^3+2)$.
My attempt is, since $f$ is a homomorphism
$$f(x^3+2)=f^3(x)+f(2)=27+f(2)$$ but what is $f(2)$?
abstract-algebra
abstract-algebra
asked 4 hours ago
paradox
444
444
3
A ring homomorphism sends the identity to the identity, hence $f(1)=1$, so $f(2)=f(1+1)=,...$
– quasi
4 hours ago
add a comment |Â
3
A ring homomorphism sends the identity to the identity, hence $f(1)=1$, so $f(2)=f(1+1)=,...$
– quasi
4 hours ago
3
3
A ring homomorphism sends the identity to the identity, hence $f(1)=1$, so $f(2)=f(1+1)=,...$
– quasi
4 hours ago
A ring homomorphism sends the identity to the identity, hence $f(1)=1$, so $f(2)=f(1+1)=,...$
– quasi
4 hours ago
add a comment |Â
1 Answer
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up vote
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As mentioned in the comments, $f(2) = f(1 + 1) = f(1) + f(1) = 1 + 1 = 2$, so $f(x^3 + 2) = 29$.
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
5
down vote
accepted
As mentioned in the comments, $f(2) = f(1 + 1) = f(1) + f(1) = 1 + 1 = 2$, so $f(x^3 + 2) = 29$.
add a comment |Â
up vote
5
down vote
accepted
As mentioned in the comments, $f(2) = f(1 + 1) = f(1) + f(1) = 1 + 1 = 2$, so $f(x^3 + 2) = 29$.
add a comment |Â
up vote
5
down vote
accepted
up vote
5
down vote
accepted
As mentioned in the comments, $f(2) = f(1 + 1) = f(1) + f(1) = 1 + 1 = 2$, so $f(x^3 + 2) = 29$.
As mentioned in the comments, $f(2) = f(1 + 1) = f(1) + f(1) = 1 + 1 = 2$, so $f(x^3 + 2) = 29$.
answered 4 hours ago
Matheus Andrade
805215
805215
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3
A ring homomorphism sends the identity to the identity, hence $f(1)=1$, so $f(2)=f(1+1)=,...$
– quasi
4 hours ago