(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Show that the imaginary part of the solution of

[itex] z''+z'+z=te^{it} [/itex] is a solution of [itex] y''+y'+y=tsin{t} [/itex]

3. The attempt at a solution

Ok so I first make the guess that [itex] z(t)=(at+b)e^{it} [/itex]

then I find z' and z'' and plug it back in and then equate the coefficients of t and then all the leftover constants.

I do this and I get a=-i and b=(2i+1)

so then I plug this in back to the original guess for z(t) and then multiply it by Eulers formula

and then take the imaginary part and see if it works for y(t). Is this the right approach.

I seem to be off by a cosine factor, I could post my work, but I just wanted to know if this is the right approach.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Undetermined coefficients

**Physics Forums | Science Articles, Homework Help, Discussion**