- #1
UrbanXrisis
- 1,196
- 1
find the particular solution for y''+25y=50sin(5t)
I am using variation of parameter:
[tex]y_p=U_1e^{5x}+U_2e^{-5x}[/tex]
[tex]y_1=e^{5x},y_1'=5e^{5x},y_2=e^{-5x},y_2'=-5e^{-5x}[/tex]
[tex]U_1=- \int \frac{e^{-5x}50sin(5t)}{-10}=-0.5e^{-5x} (cos5x+sin5x)[/tex]
[tex]U_2= \int \frac{e^{5x}50sin(5t)}{-10}=0.5e^{5x} (cos5x-sin5x)[/tex]
[tex]y_p=-0.5e^{-5x} (cos5x+sin5x) e^{5x}+ 0.5e^{5x} (cos5x-sin5x)e^{-5x}[/tex]
[tex]y_p=-sin5x[/tex]
I know this is wrong because the check doesn't equal 50sin(5t)
any ideas?
I am using variation of parameter:
[tex]y_p=U_1e^{5x}+U_2e^{-5x}[/tex]
[tex]y_1=e^{5x},y_1'=5e^{5x},y_2=e^{-5x},y_2'=-5e^{-5x}[/tex]
[tex]U_1=- \int \frac{e^{-5x}50sin(5t)}{-10}=-0.5e^{-5x} (cos5x+sin5x)[/tex]
[tex]U_2= \int \frac{e^{5x}50sin(5t)}{-10}=0.5e^{5x} (cos5x-sin5x)[/tex]
[tex]y_p=-0.5e^{-5x} (cos5x+sin5x) e^{5x}+ 0.5e^{5x} (cos5x-sin5x)e^{-5x}[/tex]
[tex]y_p=-sin5x[/tex]
I know this is wrong because the check doesn't equal 50sin(5t)
any ideas?
Last edited: