Question

shifting theorem for laplace transform of a heaviside function

Answer 1

\[f(t)=f(t)[H(t-0)-H(t-7)]+f(t)H(t-7)\]for 0<=t<7, f(t)=1; t>=7, f(t)=cos(t)\[f(t)=[H(t-0)-H(t-7)]+\cos(t)H(t-7)\]laplace of 1st part\[L[H(t-0)]-L[H(t-7)=\frac{1}{s}-\frac{e ^{-7s}}{s}\]as for the 2nd part, i am abit blur on how to apply the 2nd shifting theorem

Answer 2

\[\cos(t)H(t-7)=H(t-7)\cos(t-7+7)\]\[\cos(t)H(t-7)=H(t-7)[\cos(t-7)\cos(7)-\sin(t-7)\sin(7)]\]am i correct?

Answer 3

c

Answer 4

oh k solved. lol. got 5more question ._.