Exercise · ZW-INVERSE-LAPLACE-TRANSFORM-007 · ★★☆ Intermediate

What is \(\mathcal L^{-1}\left\{\dfrac{1}{s^2+2s+5}\right\}\)?

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  • B. \(\tfrac12e^{-t}\sin 2t\)

Explanation

Complete the square: \(s^2+2s+5=(s+1)^2+4\). Then \(\frac1{(s+1)^2+4}=\frac12\cdot\frac2{(s+1)^2+2^2}\), with inverse \(\frac12e^{-t}\sin2t\).

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Review the concept: Inverse Laplace transform

The inverse transform \(\mathcal L^{-1}\) of a function \(F(s)\) is the function \(f(t)\), defined for \(t\ge0\), whose Laplace transform is \(F(s)\).

\[f(t)=\mathcal L^{-1}\{F(s)\}\iff \mathcal L\{f\}=F\]

More practice problems: inverse laplace transform

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