# Thread: Finding interval for regula falsi method for equation "x - e^-x"

1. ## Finding interval for regula falsi method for equation "x - e^-x"

What could be the best interval with regula falsi method for equation "x - e^-x" from attached graph ?
Can anyone help ?

2. Pick one on each side. Do we need more care than that?

3. Originally Posted by tkhunny
Pick one on each side. Do we need more care than that?
I picked (-4, 4), (-4, 2), (-1, 1), (-1, 2)
but it doesn't gives solution.

Actually here minimum iterations are required to find root. This is what to care about.

4. Originally Posted by mymath007
What could be the best interval with regula falsi method for equation "x - e^-x"...?
The quoted portion is just an expression. Is the "function" meant to be "f(x) = x - e-x"? And you're trying to find the x-intercept numerically? I think that's what is indicated in the graph....

What do you mean by "the best interval"? Are you given a list of answer-options, and you're expected to pick the best one of those listed? (I mean, any interval that eventually iterates to a solution is a "good" interval, right?)

Originally Posted by mymath007
I picked (-4, 4), (-4, 2), (-1, 1), (-1, 2) but it doesn't gives solution.
What do you mean by "it"? You seem to have "picked" four intervals, rather than one. What did you do with these? On what basis have you determined that "it" ("they"?) fail(s) to lead to the solution?

Originally Posted by mymath007
Actually here minimum iterations are required to find root. This is what to care about.
I'm sorry, but I don't know what this means...? Please reply with clarification, along with a clear listing of your steps and results so far. Thank you!

5. Originally Posted by mymath007
I picked (-4, 4), (-4, 2), (-1, 1), (-1, 2)
but it doesn't gives solution.

Actually here minimum iterations are required to find root. This is what to care about.
They all give a solution. Please show your work with just ONE of the intervals.

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