Field Extensions and the Complex Numbers: Examples and Counterexamples
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✓ 7 results · all verified · 0 also independently AI-judged
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1 · Prerequisites
Abstract Algebra
- Binary Operations, Monoids, Groups and Subgroups
- Cosets, Index and Lagrange's Theorem
- Divisibility, Euclidean Domains, Principal Ideal Domains and Unique Factorisation
- Group Homomorphisms and the Isomorphism Theorems
- Ideals, Quotient Rings and the Isomorphism Theorems for Rings
- Normal Subgroups and Quotient Groups
- Polynomial Rings, the Division Algorithm and Roots
- Rings, Subrings, Integral Domains and Fields
- Simple Field Extensions and the Construction of the Complex Numbers
Number Theory
Real Analysis
2 · Logical flowchart
3 · Items
Example
ℚ(√2)≅ℚ[x]/(x²-2) with basis 1,√2
Example
The four-element field (ℤ/2)[x]/(x²+x+1)
Counterexample
ℚ[x]/(x²-1) is not a field: reducibility creates nonzero zero divisors
Example
The minimal polynomial of √2+√3 over ℚ is x⁴-4x²+1
Example
The square roots of i are ±(1+i)/√2
False statement
FALSE: the complex field admits an order making it an ordered field
Counterexample