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| | ABSTRACT ALGEBRA ON LINE: Galois Theory |
 | | To study solvability by radicals of a polynomial equation f(x) = 0, we let K be the field generated by the coefficients of f(x), and let F be a splitting field for f(x) over K. Galois considered permutations of the roots that leave the coefficient field fixed. |
 | | When we say that a polynomial equation is solvable by radicals, we mean that the solutions can be obtained from the coefficients in a finite sequence of steps, each of which may involve addition, subtraction, multiplication, division, or taking nth roots. |
 | | There exists a polynomial of degree 5 with rational coefficients that is not solvable by radicals. |
| www.math.niu.edu /~beachy/aaol/galois.html (1898 words) |
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