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Thread: HW General Solution for Differential Equation

  1. #1
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    HW General Solution for Differential Equation

    HW General Solution for Differential Equation-help.png

    I do not know why my answer is wrong. I keep doing the problem again and again and get the same answer...


    r''(t)=<e^t,sint,cost>
    r'(t)=<e^t,cost,-sint>
    r(t)=<e^t,-sint,-cost>

    r(0) =<1,0,-1> + c2 = <4,0,5> ---> c2 = <3,0,6>
    r'(0)=<1,1,0> +c1 = <0,3,5> --> c1=<-1,2,5>

    ANS: r(t)=<e^t-t+3,-sint+2t,-cost+5t+6>
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  2. #2
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    Re: HW General Solution for Differential Equation

    Quote Originally Posted by lc99 View Post
    Click image for larger version. 

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    I do not know why my answer is wrong. I keep doing the problem again and again and get the same answer...


    r''(t)=<e^t,sint,cost>
    r'(t)=<e^t,cost,-sint>
    r(t)=<e^t,-sint,-cost>

    r(0) =<1,0,-1> + c2 = <4,0,5> ---> c2 = <3,0,6>
    r'(0)=<1,1,0> +c1 = <0,3,5> --> c1=<-1,2,5>

    ANS: r(t)=<e^t-t+3,-sint+2t,-cost+5t+6>
    I get $r(t)=\left<e^t-t+3,4t-\sin(t).-\cos(t)+5t+6\right>$
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  3. #3
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    Re: HW General Solution for Differential Equation

    Oh my god, I did the derivative twice instead of the integral... Thanks!
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