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Thread: sovle the differential equation, basic .:Resolve:.

  1. #1

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    Hyperactive Member voidflux's Avatar
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    sovle the differential equation, basic .:Resolve:.

    hello everyone, I'm having troubles figuring out this problem and i'm trying to study for a test but its an even number and I have no idea what the answer is. THe problem is:
    Code:
    f''(x) = sinx, f'(0) = 1, f(0) = 6;
    I understand how to do non-trig ones
    f''(x) = 2, f'(2) = 5, f(2) = 10
    f'(x) = 2x + c1;
    f'(2) = 2(2) + c1;
    5 = 4 + c1;
    c1 = 1.
    f'(x) = 2x+1;
    f(x) = x^2+1x+c2;
    f(2) = 2^(2)+1(2)+c2;
    10 = 6 + c2
    c2 = 4;
    f(x) = x^2+x+4

    I"m getting:
    f(x) = -sinx+2x+6
    which i htink is right i just want a double check on this
    Last edited by voidflux; Dec 4th, 2003 at 03:49 PM.
    C¤ry Sanchez
    Computer Science/Engineering
    @ Penn State
    IBM.zSeries Intern
    Mandriva 2007

  2. #2
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    f''(x) = sinx

    Integrate both sides w.r.t. x:

    f'(x) = -cosx + c

    Since f'(0) = 1, c = 2

    f'(x) = 2 - cosx

    Integrate both sides w.r.t. x:

    f(x) = 2x - sinx + c

    Since f(0) = 6, c =6

    f(x) = 2x - sinx + 6

  3. #3

    Thread Starter
    Hyperactive Member voidflux's Avatar
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    Thumbs up

    Thanks!
    C¤ry Sanchez
    Computer Science/Engineering
    @ Penn State
    IBM.zSeries Intern
    Mandriva 2007

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