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Aerospace93
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Homework Statement
y''+2y'+y=xe-x
Homework Equations
Yc=c1e-x+c2xe-x
relevant info on textbook: "If any term of yp is a solution of the complementary equation, multiply yp by x (or by x2 if necessary)."
>> i don't understand the part where it says "a solution of the complementary equation". Does it mean that if any term in yp is equal to any term in the complementry solution[...]? or does it explicitly mean if any term in yp is equal to the entire solution of the complementary equation[...]?
The Attempt at a Solution
The first particular solution that pops when G(x)=xe-x is yp=(Ax+b)e-x. However, since that gives a particular equation whose terms are in the complementary equation we must multiply by x.
seconds attempt: yp=x(Ax+b)e-x.
Now what i didn't understand above comes into play. There is a term in the particular solution bxe-x which is equal to another SINGLE TERM (maybe what they refer to as a solution?) in the complementary solution c2xe-x. Does this mean i must multiply by x2?
that would be: yp=x2(Ax+b)e-x... now no single term in the particular sol. is equal to a single term in the complementary solution.
disclaimer: my confusion is with the language used. when they refer to a solution of the complementary equation are they referring to anyone term in the equation and calling that a solution or are they referring to the complementary eq. as a whole? I'm confused :s and my instincts tell me that they could have used "term" instead of "solution" there too... fml