I need a little help solving this problem by using newtons method:

Find x where y=6e^-x+6e^-2x+106e^-3x

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- May 6th 2009, 09:14 AMLuck of the IrishNewtons Method
I need a little help solving this problem by using newtons method:

Find x where y=6e^-x+6e^-2x+106e^-3x - May 6th 2009, 12:05 PMShowcase_22
Do we have to rearrange it to make x the subject or does y equal something?

- May 6th 2009, 01:05 PMSpec
I'm guessing it's $\displaystyle y=f(x)$, so we use Newton-Raphson's method to find the root.

$\displaystyle x_{n+1}=x_n - \frac{f'(x_n)}{f(x_n)}$

Try using $\displaystyle x_0 = 4$ - May 6th 2009, 01:09 PMTwig
- May 6th 2009, 01:17 PMSpec
Right, good catch.

- May 6th 2009, 08:41 PMLuck of the Irish
so apply that formula and im good?

- May 7th 2009, 11:43 AMTwig
You might have to do a few iterations to get close enough to the solution.

- May 7th 2009, 02:07 PMHallsofIvy