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Roots of implicit equations

by tom92373
Tags: equations, functions, implicit, roots
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Jan30-09, 09:48 PM
P: 4
I was working on double integrals when I came across the equation: x^(3/2)=sin(x).
There was no noticeable way to isolate the equation for x without having a function of x equal to x. I am wondering how to isolate equations involving logs, sines, etc when it is given in an implicit form.
Using a computer, I was able to get an approximation of 0 and 8.02... How do I get the EXACT value of x?
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Jan30-09, 10:52 PM
qntty's Avatar
P: 290
I don't think that can be solved analytically, numerical approximations are the best you can get.
Jan30-09, 11:12 PM
Sci Advisor
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P: 3,684
There's no reason to expect a nice solution to that equation.

To 500 decimal places:
0.802803731737889315511835324604000441222668910616527410810139645656916 41862577997739822547061430396268572323604994666281323668533410644604205 80146429193050351847866748648721823651393578239737490947961432790796313 11192258789712012684896470290853854071877856944549231720563315930180837 75727247023723969536341968998158469732909155080566871504200160137298683 45016085397258496851256650987721510001930807383556524999088268285074848 68972435998828725360089377601379653239348761648787005801149203560836827 42718

Jan31-09, 09:52 PM
P: 90
Roots of implicit equations

How did you get an answer to 500 decimal places?!
Feb1-09, 06:46 AM
P: 534
Mathematica (for example) can do it.
Feb1-09, 07:17 AM
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What's wrong with x=0 as an exact solution??

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