622 ANSWERS
Section 12 .6. Laplace Transforms of Derivatives and Integrals:
page 552
1. .C (sint) = 8 2~ 1.
3. .C (sin^2 t) = s(sf+4).
.c- 1 ( s(s - 4) l ) = _! 4 + !e 4 4t.
.c-^1 ( • 2 (;+ 1 )) = t - 1 +ct.
y(t) = 2cos3t+3sin3t.
11. y(t) = - 2 + 2cos2t+ sin2t.
13. y(t) = 2 +et.
- y(t) = -1-~e-t +~et= -1 + sinht +et.
- y(t) = e-^2 t + et.
Section 12. 7. Shifting Theorems and the Step Functions: page 557
1. .C (et - tet) = (s:::h2 + .~1.
3. .C (eat cosbt) = (s-:)f+b•.
- f(t) = .c-^1 (.2~~;+s) = e-^2 t cost.
(^7). f(t) = .c-^1 ( (s+2J2H •+^3 ) = e-^2 t cost+ e-^2 tsint.
9. .C ( U 2 (t) (t - 2)
2
) =^2 ·.~··.
11. .C (U3" (t)sin(t- 37r)) = ~;~;.
.C (f(t) = ~(l - 2e-• + 2e-^2 • - e-^3 •).
.c-^1 ( .-·~·-") = U1 (t) + U2 (t).
1 7. y(t) = - e- tcost.
- t. t
- y(t) = 2eT Slll 2·
- y(t ) = t^3 e- t.
- y(t) = [1 -o(t -~)) sint + (1-sint)U~ (t).