Laplace transform involving the unit step function and an exponential

Ke^{ - at} u(t) \Leftrightarrow \frac{K}{{s + a}}

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% amiDaiaacMcacqGHuhY2daWcaaqaaiaadUeaaeaacaWGZbGaey4kaS
% Iaamyyaaaaaaa!43E5!

Pasting the above "text" into MathType 5.0 will enter the above equation and make it possible to edit, save, and use in applications such as MS Word.