## Thomas' Calculus 13th Edition

Multiplication $e^{-cx}$ by $c$ produces a probability density density on $[0,\infty)$
$\int^\infty_0e^{-cx}dx$ =$\frac{1}{c}\lim\limits_{b \to \infty}(-e^{-bcx}+1)$=$\frac{1}{c}$ Multiplication $e^{-cx}$ by $c$ produces a probability density density on $[0,\infty)$