Errors reported for the smaple exam 3 key, F2008.

Tanner Fullmer reported two errors [2 Dec]: Problem (4b) (the second b)
it shows that a=3,b=4,c=0,d=5. It should be a=3, b=4, c=5, d=0. Problem
(4c)(second c) key shows the original denominator as (s+2)^3 when from
the problem the denominator should be (s+2)^4. 

Problem (5b) has no key, because these problem types have been removed
from midterm 3. To work such problems, write the problem as
2tf(t)=exp(2t)sin(t)-exp(-2t)sin(t). Then
-2(d/ds)F(s)=1/((s-2)^2+1)-1/((s+2)^2+1) can be solved as a first order
quadrature equation with solution F(s)=0.5(arctan(s+2)-arctan(s-2))+c.
The value of c=0, because limit F(s) =0 as s -> infinity. See also final
exam keys from S2008.