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Mathematics 18 Online
OpenStudy (anonymous):

Solve DE by reduction to constant coefficients

OpenStudy (anonymous):

\[x^2y''-3xy'+13y=4+3x\]

OpenStudy (anonymous):

i did quadratic and used reductio nto find the y_c which is correct

OpenStudy (anonymous):

\[y_c=x^2(c_1cos(3ln(x)+c_2sin(3ln(x))\]

OpenStudy (anonymous):

\[y_p=Ax+B\] \[y_p'=A\] \[y_p''=0\]

OpenStudy (anonymous):

switch the x with t

OpenStudy (anonymous):

\[y''-4y'+13y=4+3t\] \[0-4A+13At+13B=4+3t\]

OpenStudy (anonymous):

\[0-4A+13Ax+13B=4+3x\] \[0-4a+13Ae^t+13B=4+3e^t\]

OpenStudy (anonymous):

is ther aything wrong with this?

OpenStudy (anonymous):

because this was exactly what i did and i still come out with the wrong answer

OpenStudy (anonymous):

@amistre64

OpenStudy (anonymous):

I can't figure out why these answers are coming out wrong?

OpenStudy (amistre64):

2 months of summer vacation, id have to read up on this to refresh

OpenStudy (anonymous):

the complementary is correct but idk how to do the nonhomogeneous. my book simply says use the new equation and solve using the procedures from a few sections however that doesn't work

OpenStudy (amistre64):

wronskian works if youve got the homogenous part

OpenStudy (anonymous):

yes but idk if thta's what it wants me to do

OpenStudy (anonymous):

it says sub x=e^t to get it with constant coefficients

OpenStudy (anonymous):

i do that

OpenStudy (anonymous):

and i get my complementary.. Since it's in constant coefficients ican use superposition

OpenStudy (anonymous):

with \[y_p=Ax+B\]

OpenStudy (anonymous):

however when i do this i get a completely different answer than the book and i have no idea how they got it

OpenStudy (anonymous):

that is my book-.-

OpenStudy (amistre64):

:)

OpenStudy (amistre64):

ok, so are you sire youre Yc is good?

OpenStudy (anonymous):

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