Find the (L^{-1} ( frac{s}{2s+9+s^2}) ).

1.	Find the (L^{-1} ( frac{s}{2s+9+s^2}) ).
A.	(e^{-t} {cos u2061(2 sqrt{2t})-sin u2061( sqrt{2t}) } )
B.	(e^{-t} {cos u2061(2 sqrt{2t})-sin u2061(2 sqrt{2t}) } )
C.	(e^{-t} {cos u2061(2 sqrt{2t})-cos( sqrt{2t}) } )
D.	(e^{-2t} {cos u2061(2 sqrt{2t})-sin u2061(2 sqrt{2t}) } )
Answer» C. (e^{-t} {cos u2061(2 sqrt{2t})-cos( sqrt{2t}) } )

Discussion

The (L^{-1} left ( frac{3s+8}{s^2+4s+25} right ) ) is (e^{-st} (3cos ( sqrt{21}t+ frac{2sin ( sqrt{21}t)}{ sqrt{21}}) ). What is the value of s?
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