How to use goalseek to find solutions to equation?

Originally Posted by thaopham

How do I find the solutions to this equation using goalseek?

Hi

Can you clarify some points?

1 - Why do you have to use goal seek? Why not just find the solutions of the equation?

2 - Do you always need to solve a 3rd degree equation?

3 - Would a UDF solution be acceptable?


This is a 3rd degree equation and so can have either:

- 3 real roots
- 1 real root and 2 complex ones

Also the real roots can be equal, for example 2 roots equal and the 3rd different.

This means that if you use goalseek, you must do some work before.

A UDF solution would be easier since you wouldn't need to do any analysis of the equation.


If you want to use goal seek, you did not specify exactly where you have problems, so here are 2 links:

If you never used goalseek:

http://www.dummies.com/how-to/conten...k-feature.html

An example to finding the roots of a polynomial using goalseek:

http://people.revoledu.com/kardi/tut...olynomial.html

HTH