简单分析一下,答案如图所示
lim(x->+∞) [ f(x) - a1x]
=lim(x->+∞) [ (x-1)e^(π/2+arctanx) - x.e^π]
=lim(x->+∞){ [ x[ e^(π/2+arctanx) -e^π] - e^(π/2+arctanx) }
=-e^π + lim(x->+∞) x[ e^(π/2+arctanx) -e^π]
=-e^π + lim(x->+∞) [ e^(π/2+arctanx) -e^π] /(1/x) (0/0)
=-e^π + lim(x->+∞) [ 1/(1+x^2) ]e^(π/2+arctanx) /(-1/x^2)
=-e^π + lim(x->+∞) -[ x^2/(1+x^2) ]e^(π/2+arctanx)
=-e^π - lim(x->+∞) e^(π/2+arctanx)
=-2e^π