y = x/(1+x^2)
= [(1+x^2) - 2x^2]/(1+x^2)^2
=( 1- x^2)/(1+x^2)^2
y'=0
x=1 or -1
y'|x=1+ <0
y'|x=1- >0
x=1 (max)
y'|x=-1+ >0
y'|x=-1+ <0
x=-1 (min)
y(1) = 1/2
y(-1)=-1/2
lim(x->+â) y =lim(x->+â) x/(1+x^2) = 0
lim(x->-â) y =lim(x->+â) x/(1+x^2) = 0
|y| â¤f(1) =1/2
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