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Thread: Pls help! tomorrow i have EXAM! help in homework! :(

  1. #1
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    Arrow Pls help! tomorrow i have EXAM! help in homework! :(

    hello

    could you pls write for me ONLY general and particular solution of these Second order Inhomogeneous solutions? i know that SOLUTION for Second order Inhomogeneous is PARTICULAR solution + GENERAL solution.

    Here they are (this is image because i took PRINT SCREEN)



    Uploaded with ImageShack.us

    Thank You!
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  2. #2
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    Quote Originally Posted by kabal View Post
    hello

    could you pls write for me ONLY general and particular solution of these Second order Inhomogeneous solutions? i know that SOLUTION for Second order Inhomogeneous is PARTICULAR solution + GENERAL solution.

    Here they are (this is image because i took PRINT SCREEN)



    Uploaded with ImageShack.us

    Thank You!
    Pick a problem because I am not doing them all.
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  3. #3
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    could you please do this one?

    Click on the image to ZOOM in



    I dont want whole answer, i neew only PARTICULAR solution for this.

    THANK YOU
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  4. #4
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    Quote Originally Posted by kabal View Post
    could you please do this one?

    Click on the image to ZOOM in



    I dont want whole answer, i neew only PARTICULAR solution for this.

    THANK YOU
    Have you solved the complementary solution first, 2\frac{d^2x}{dt^2}-2\frac{dx}{dt}+5x=0?

    To solve the particular solution, we need to know what annihilates e^{-2t}(2sin(2t)+3cos(t)); therefore, what annihilates that expression?
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  5. #5
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    i got roots of 2k^2-2k+5=0

    roots are: k1=0.5+3/2i k2=0.5-3/2i

    General Solution is: e^0.5t(C1cos3/2t+C2sin3/2t)

    Particular solution is: e^-2t(Asin2t+Bcost)

    is it correct?
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  6. #6
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    Quote Originally Posted by kabal View Post
    i got roots of 2k^2-2k+5=0

    roots are: k1=0.5+3/2i k2=0.5-3/2i

    General Solution is: e^0.5t(C1cos3/2t+C2sin3/2t)

    Particular solution is: e^-2t(Asin2t+Bcost)

    is it correct?
    I tend to use the annihilator method.

    e^{-2t}(2sin(2t)+3cos(t)) is annihilate by (D^2+2)(D+1) or (D+2)^2+1. You are going to have to check it since I loaned out my DE book.
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