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Algebra .. equation


Mark Nazzal

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Use Newton's method (calculus)

 

Basically get an estimate/guess of X (say .2), then keep doing the iteration below (computer recommended for sanity).

 

Xn+1 = Xn- f(Xn)/f'(Xn)

 

f(x) = -4x^3+3x-1/2

f'(x) is the derivative of f(x)

 

Successive X's will be converge to the "real" root (they get more accurate each time), so keep doing it until it's accurate enough for you.

 

Here's a short cut:

 

http://www.math.sc.edu/cgi-bin/sumcgi/Newton.pl

 

Answer: x=0.17364817766693

 

 

Edit: Here's an explanation (semi-proof) why Newton's method works. Stop reading just after equation (5), we're not really interested in the rest (and it gets ugly too).

Spreading beauty with my katana.

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