Solving Polynomials: Hints, Techniques & Solutions

In summary, the conversation is about solving a complicated equation involving trigonometric functions and rational expressions. The person asking for help has tried using numerical methods but would prefer an analytic approach. However, it is concluded that there is no easy way to solve this equation and a numerical technique is the best approach. The equation is not a polynomial and a simplification provided by another person is deemed not very useful.
  • #1
ts547
8
0

Homework Statement



Solve for x,

225*sin(x)/x^6-225*cos(x)/x^5-90*sin(x)/x^4+15*cos(x)/x^3-5/(2*x^3)=0


Homework Equations



Finding this very complicated to solve, are there any useful hints or techniques we should know about?


The Attempt at a Solution



Have used numerical method using mathematics software and plotted a graph to identify where the function crosses the x-axis. Would prefer a more analytic approach.

Thank you in advance.
 
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  • #2
ts547 said:

Homework Statement



Solve for x,

225*sin(x)/x^6-225*cos(x)/x^5-90*sin(x)/x^4+15*cos(x)/x^3-5/(2*x^3)=0


Homework Equations



Finding this very complicated to solve, are there any useful hints or techniques we should know about?


The Attempt at a Solution



Have used numerical method using mathematics software and plotted a graph to identify where the function crosses the x-axis. Would prefer a more analytic approach.

Thank you in advance.

I think that you are out of luck regarding an analytic solution.

BTW, is this your equation?
[tex]225\frac{sin(x)}{x^6} - 225 \frac{cos(x)}{x^5} - 90\frac{sin(x)}{x^4} + 15\frac{cos(x)}{x^3} - \frac{5}{2x^3} = 0[/tex]
 
  • #3
Yeh that's it. I haven't learned how to do the fancy writing yet. I didnt think there would be an easy way of doing this.
 
  • #4
Unless there's some funny trick to recognize here, there's no way to solve this algebraically. It's best to use a numerical technique. i.e. Bisection method, Newton's method, etc.
 
  • #5
ts547 said:
Yeh that's it. I haven't learned how to do the fancy writing yet. I didnt think there would be an easy way of doing this.
You can see the LaTeX I wrote by clicking the equation.
 
  • #6
Heck, I managed to simplify it this equation (check work?):

[tex]
(\frac{15}{x^3} - \frac{6}{x})sin(x) + (1 - \frac{15}{x^2})cos(x) = \frac{1}{6}
[/tex]

Edit: LaTeX isn't the easiest, heh. Also, I'm not sure that simplification is even very useful.
 
  • #7
I hope that you are aware that this is not a matter of "solving polynomials"! The equation you give is not a polynomial.
 
  • #8
Apphysicist - Haha good simplification. Not very useful I don't think. :) Never mind ill stick with the numerical approach.

HallsofIvy - Ok no its not a polynomial. Didnt know what else to call it at the time. If your so clever help me with this

https://www.physicsforums.com/showthread.php?p=3075732#post3075732

then you can point out technicalities all you want.
 

1. What is a polynomial?

A polynomial is an algebraic expression that consists of variables and coefficients, combined using addition, subtraction, and multiplication, but never division, exponents, or radicals.

2. What are the different techniques for solving polynomials?

Some common techniques for solving polynomials include factoring, using the quadratic formula, and using long division or synthetic division. Other methods include graphing and using the rational roots theorem.

3. How do you know if a polynomial has any solutions?

A polynomial has solutions if and only if it has at least one real root, which is a value for the variable that makes the polynomial equal to zero. This can be determined by graphing the polynomial or by using the rational roots theorem.

4. Can all polynomials be solved using the same techniques?

No, not all polynomials can be solved using the same techniques. The methods used to solve a polynomial depend on its degree (the highest exponent) and its form. For example, a polynomial with a degree of 2 (quadratic) can be solved using the quadratic formula, while a polynomial with a degree of 3 (cubic) can be solved using the cubic formula.

5. Are there any tips or hints for solving polynomials more efficiently?

One tip for solving polynomials more efficiently is to always start by factoring, if possible. This can help simplify the polynomial and make it easier to solve. Another tip is to look for patterns or common factors in the polynomial, as this can also make solving it easier.

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