= (-1)^2 (d^2/ds^2) laplace(cos(t))
= (d^2/ds^2) (s/(s^2+1))
= (d/ds) [-2s^2(s^2+1)^-2 + (s^2+1)^-1]
= 8s^3/ (s^2+1)^3 - 6s/(s^2+1)^2
thats the answer i got but the answer in the book says (2s^3 - 6s)/ (s^2+1)^3
where did i go wrong?
= (-1)^2 (d^2/ds^2) laplace(cos(t))
= (d^2/ds^2) (s/(s^2+1))
= (d/ds) [-2s^2(s^2+1)^-2 + (s^2+1)^-1]
= 8s^3/ (s^2+1)^3 - 6s/(s^2+1)^2
thats the answer i got but the answer in the book says (2s^3 - 6s)/ (s^2+1)^3
where did i go wrong?