A time-to-failure distribution is said to have a Weibull distribution if the cumulative distribution function is given by F(t) = 1 et / , where

A time-to-failure distribution is said to have a Weibull distribution if the cumulative distribution function is given by
F(t) = 1 –e–tβ /ƞ , where ƞ, β > 0.
Find the failure rate, and show that the Weibull distribution is IFR when β ≥ 1 and DFR when 0 < β ≤ 1.