- #1
angel
- 18
- 0
ok
im trying to solve the following equation using standard aux method:
d^2y/dx^2 + 3dy/dy +2y = cos x with conditions x(0)=-3 and x'(0) = 3
my aux eqn is:
ae^x + be^-2x
and my yp is;
a sin kx + b cos kx
i differentiate this twice and substitute into the original equation, and i get:
(-a sin x - b cos x)+3(a cos x-b sin x) + 2(a sin x+ b cos x) = cos x.
Now at this stage I am not sure if this is right or not, can someone please confirm if this is right or not.
I ve done this question using the laplace method and the answer i get is;
-19/2e^x +32/5 e^2x + 1/10 cos x - 3/10 sin x.
Here my aux equation is not the same as what i get when i apply the laplace method.
Im not sure what is going wrong.
Someone help me please.
im trying to solve the following equation using standard aux method:
d^2y/dx^2 + 3dy/dy +2y = cos x with conditions x(0)=-3 and x'(0) = 3
my aux eqn is:
ae^x + be^-2x
and my yp is;
a sin kx + b cos kx
i differentiate this twice and substitute into the original equation, and i get:
(-a sin x - b cos x)+3(a cos x-b sin x) + 2(a sin x+ b cos x) = cos x.
Now at this stage I am not sure if this is right or not, can someone please confirm if this is right or not.
I ve done this question using the laplace method and the answer i get is;
-19/2e^x +32/5 e^2x + 1/10 cos x - 3/10 sin x.
Here my aux equation is not the same as what i get when i apply the laplace method.
Im not sure what is going wrong.
Someone help me please.