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hi can u help me write out the formula for the equation below using the Newton-Raphson method?

cosx=1.6x^1.3 when x≥0,in radians

Thanks!!

2 Answers

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  • cidyah
    Lv 7
    1 decade ago
    Favorite Answer

    f(x)= cos x - 1.6 x^3

    We want to solve f(x)=0 for x.

    f'(x)=-sin x -1.6 (3x^2)

    f'(x) = -sin x -4.8 x^2

    Start the process with an initial approximation x0=1 (you may choose any reasonable value)

    First approximation:

    x1 = x0- f(x0) / f'(x0)

    x1 = 1 - f(1) / f'(1)

    f(1)= cos(1)-1.6(1)^3 =-1.0596976941

    f'(1)=-sin(1)-4.8(1)^2 =-3.958529015

    x1= 1 - [-1.0596976941] /[-3.958529015]

    x1 = 0.81215933

    Repeat the process with x1

    x2= x1 - f(x1) / f'(x1)

    and continue until the difference between two successive approximations is less than, say .00001

    x = 1.00000000 -1.0596976941

    x = 0.81215933 -0.1691912247

    x = 0.76868631 -0.0078959742

    x = 0.76645039 -0.0000202264

    x = 0.76644463 -1e-10.0000000000

    The process converges to 0.76644463

    x=0.76644463

    x= 0.76644463

  • 1 decade ago

    f(x) = cos x - 1.6 x^1.3

    f '(x) = - sin x -1.6*1.3 x^.3 = - sin x - 2.08 x^.3

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

    xn __________________ f(xn) ______ f '(xn)

    1 __________________ -1.05970 ___ -2.92147

    0.637272559049036 ___ -0.08700 ___ -2.41203

    0.601202693915652 ___ -0.00109 ___ -2.35117

    0.600738500498314 ___ -0/2 _______ -2.35038

    0.600738421844613 ___ +0 ________ -2.35038

    0.600738421844611 ___ 0 _________ -2.35038

    0.600738421844611 ___ 0 _________ -2.35038

    0.600738421844611 ___ 0 _________ -2.35038

    0.600738421844611 ___ 0 _________ -2.35038

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