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Differential Equation

Started by Thunder_Hawk Jan 19, 2006 at 4:37 PM 3 replies 3.8k views

Original Post

Jan 19, 2006 at 4:37 PM

WARNING HOMEWORK PROBLEM: I have stumbled across a very strange integration problem. I'm trying to find all of the solutions to the equation y"+9y=sin(3x) That's all fine, well, and good, except part of the problem requires me to integrate the equation u₁'(x) = -i/6*e^(-3ix)sin(3x) and another of the same basic form I'm positive that the integral of e^(ax)sin(bx) = e^(ax)/(a^2+b^2)*(a*sin(bx)-b*cos(bx)), but in this case a^2+b^2 = 0, leaving the integral undefined...any ideas??

twanvl

Jan 19, 2006 at 4:52 PM

Since you could have done this yourself: The wolfram integrator has the answer, but not the intermediate steps.

Thunder_Hawk

Jan 19, 2006 at 4:59 PM

Sorry, I forgot to mention that I used maple to find an answer. I'm just trying to figure out how to arrive at an answer. It seems that I need to take a closer look at the specific integration that creates this problem, however, the only method I see to solve it is using integration by parts to obtain an algebraic equation that I can solve for the integral, which is what led me to the a^2 + b^2 denominator in the first place.

grhodes_at_work

Jan 19, 2006 at 5:18 PM

Homework/schoolwork problems violate forum policy. Read the Forum FAQ. Thread closing.

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