Algebraic solution

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An algebraic solution is an algebraic expression which is the solution of an algebraic equation in terms of the coefficients of the variables. It is found only by addition, subtraction, multiplication, division, and the extraction of roots (square roots, cube roots, etc.).

The most well-known example is the solution of the general quadratic equation.


x=\frac{-b \pm \sqrt {b^2-4ac\  }}{2a},
ax^2 + bx + c =0\,

(where a ≠ 0).

There is a more complicated solution for the general cubic equation[1] and quartic equation.[2] The Abel-Ruffini theorem[3]:211 states that the general quintic equation does not have an algebraic solution. This means that the general polynomial equation of degree n, for n ≥ 5, cannot be solved by using algebra. However, under certain conditions, we can get algebraic solutions; for example, the equation x^{10} = a can be solved as x=a^{1/10}.

References[change | edit source]

  1. Nickalls, R. W. D., "A new approach to solving the cubic: Cardano's solution revealed," Mathematical Gazette 77, November 1993, 354-359.
  2. Carpenter, William, "On the solution of the real quartic," Mathematics Magazine 39, 1966, 28-30.
  3. Jacobson, Nathan (2009), Basic Algebra 1 (2nd ed.), Dover, ISBN 978-0-486-47189-1