Multiple solver answers

  • Thread starter Thread starter Les Coover
  • Start date Start date
L

Les Coover

Can you use Solver or some other technique to list all the values
where a function equals zero, not just one value?

For example 15x^4 - 75x^2 + 60 equals zero at -2, -1, 1, and 2

What would be the best way to determine the lowest and
highest values for x where y = 0?

Or, alternatively, to list all the values where y = 0?



Les
 
There is not a built in way to find all zeros to to a polynomial. After
you find one zero, you could either factor out that root, or add Solver
constraints to bound the search pattern away from the known root.

Jerry
 
Les Coover said:
Can you use Solver or some other technique to list all the values
where a function equals zero, not just one value?

For example 15x^4 - 75x^2 + 60 equals zero at -2, -1, 1, and 2

What would be the best way to determine the lowest and
highest values for x where y = 0?

Or, alternatively, to list all the values where y = 0?
Click to expand...

In the example above, the simplest way is to divide through by 15 to get

x^4 - 5 x^2 + 4 = 0

then use change of variables, y = x^2, to get

y^2 - 5 y + 4 = 0

which has roots 1 and 4 in y, so 1, -1, 2, -2 in x. This is an example of
the general rule that any algebraic simplification you can make you should
make.
 
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