Download Free PDF. An elementary evaluation of a quartic integral Scientia, Victor H. Download PDF. A short summary of this paper. An elementary evaluation of a quartic integral. Moll, and Sarah Riley Abstract. Introduction Honors Integral Calculus is a course taught at Tulane University to the best in- coming students. Most of them are proficient at the mechanical aspects of single variable Calculus. In the discussion on definite integrals we encouraged the students to use both tables of integrals such as Gradshteyn and Ryzhik [10] and the symbolic integration package Mathematica 5.
After covering techniques of integration we looked at Wallis formula 2. This prompted a discussion of the divisibility properties of the binomial coefficients. We proved that the central binomial coefficients Cm are always even and that 21 Cm is odd if and only if m is a power of 2; the proof we gave is outlined in Section 3.
A direct Mathematica calculation of Wallis integral gives 4. Primary Key words and phrases. Integrals, rational functions. This result provides an excellent opportunity to introduce students to the wonderful world of proving identities by machine, which is described in the beautiful book [13] where the sum 1. Details are given in Section 2. Many more examples of interesting Mathematics encountered while trying to eval- uate definite integrals can be found in our book Irresistible Integrals: Symbolics, Anal- ysis and Experiments in the Evaluation of Integrals.
The motivation of the work pre- sented here and in [6] is to provide all proofs of the evaluations appearing in the table [10]. This table contains a large number of formulas but the Mathematics be- hind their proofs is not directly available.
In each new edition, the editors include additional evaluations and the number of integrals evaluated there is very large. In our task to prove them we have chosen first those that are connected to our work. For example, in the last edition in the year one finds a beautiful formula: let 4x2 1. Unfortunately 1. This error now yields two new problems. The direct problem: find a variation of the right hand side in 1.
The inverse problem deals with the issue of typos: perhaps the number 4 appear- ing in the integrand in 1. We cannot solve either one of them. The proof of 2. In order to motivate the calculations described in Section 6, we present a new proof of Wallis formula. The inductive proof of 2. Thus 2. This can be done mechanically using the theory developed by Wilf and Zeilberger, which is explained in [12, 13]; the sum in 2.
Note that 2. The quadratic denominators The expression 2. We now show that the central binomial coefficient Cm appearing in 2. The central binomial coefficient Cm is even, and 2 Cm is odd precisely when m is a power of 2. The proof is based on the expression for the power of 2 that divides m!. In the product defining m! Note that the sum is finite. Clearly 3. Integration by parts produces the functional equation 4. A Beta function calculation We next evaluate an extension of 2.
Reduction to a polynomial In this section we prove that, apart from a simple algebraic factor, the integral N0,4 a; m is a polynomial in a.
Theorem 6. We now compute the integral appearing in 6. Some examples. Using Theorem 6. We start by reversing the order of summation in 6.
The last step is to restrict the ranges of the sums in 7. For each pair of values m, l , the evaluation of 7. The quartic denominators The expression 7. Define dmax to be the maximum exponent of 2 that appears in the denominator of dl m.
From 7. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Who found the proof for the quartic formula? Ask Question. Asked 1 year ago. Active 1 month ago. Viewed times. Matheinstein Matheinstein 3 3 bronze badges. Then at the very end how you use that to solve the quartic in just a few minutes.
Have a look. Spoiler: No one found that formula. They simplified the problem, solved the simplified problem, then transformed back. Note how many terms and expressions in your formulas are basically the same, only with a sign change here and there. That's the result of loads of simplifying substitutions. Add a comment. Active Oldest Votes. Edit: As correctly pointed out by the comment of WhatsUp, Ferrari discovered first, how to find the roots of a quartic equation.
Eldar Sultanow Eldar Sultanow 1 1 silver badge 9 9 bronze badges. I knew that Ferrari and later Cardano discovered the formula for solving cubic equations called Cardano Formula.
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