Epigraph (mathematics) and Algebraic solution: Difference between pages

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[[Image:Epigraph convex.svg|right|thumb|300px|A function (in black) is [[convex function|convex]] if and only if the region above its [[graph]] (in green) is a [[convex set]].]]
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 (mathematics)|division]], and the extraction of roots (square roots, cube roots, etc.).


In [[mathematics]], the '''epigraph''' of a [[Function (mathematics)|function]] is the set of paired values so the output of the function at the first value is [[less than or equal to]] the second value.  In math terms this means <math>(x,r) \in \operatorname{epi}(f)</math> [[if and only if]] <math>f(x) \leq r</math>.
The most well-known example is the solution of the general [[quadratic equation]].


:<math>
x=\frac{-b \pm \sqrt {b^2-4ac\  }}{2a},</math>


{{Math-stub}}
:<math>ax^2 + bx + c =0\,</math>


[[Category:Mathematics]]
(where ''a'' ≠ 0).
 
There is a more complicated solution for the general [[cubic equation]]<ref>Nickalls, R. W. D., "A new approach to solving the cubic: Cardano's solution revealed," ''Mathematical Gazette'' 77, November 1993, 354-359.</ref> and [[quartic equation]].<ref>Carpenter, William, "On the solution of the real quartic," ''Mathematics Magazine'' 39, 1966, 28-30.</ref>  The [[Abel-Ruffini theorem]]<ref>Jacobson, Nathan (2009), Basic Algebra 1 (2nd ed.), Dover, ISBN 978-0-486-47189-1</ref>{{rp|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 <math>x^{10} = a</math> can be solved as <math>x=a^{1/10}.</math>
 
==References==
{{reflist}}
 
{{DEFAULTSORT:Algebraic Solution}}
[[Category:Algebra]]

Latest revision as of 19:16, 12 March 2013

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.

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

(where a ≠ 0).

There is a more complicated solution for the general cubic equation[1] and quartic equation.[2] The Abel-Ruffini theorem[3]Template:Rp 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 [math]\displaystyle{ x^{10} = a }[/math] can be solved as [math]\displaystyle{ x=a^{1/10}. }[/math]

References

Template:Reflist

  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