$5.(4\mathrm{.}9-4$a$,$CALC$)$Theimproperintegral $0$ f$($x$)$dxcannotbeconvertedintoanintegralwithfinitelimits usingthesubstitutiont$=1/$xbecausethelimitatzerobecomes infinite.Theproblemisresolvedby firstwriting $0$ f$($x$)$dx$=10$ f$($x$)$dx$+$ $1$ f$($x$)$dx$.$Applythistechniquetoapproximatethefollowing improperintegral towithin$106$ a$.$ $011+$x$4$dx