Question 997691
{{{k(x)=1/(x^2+5)}}}...this function is defined for all {{{x}}} except one that makes denominator equal to zero and that is {{{x=sqrt(5)}}} or approximately {{{x=2.24}}}

max{{{1/(x^2+5) = 1/5}}} at {{{x = 0}}}, in your case {{{a}}}

so, 
from {{{-infinity}}} to {{{a}}} function is increasing

and from {{{a}}} to {{{infinity}}} function is decreasing


interval where function is increasing is: ({{{-infinity}}},{{{a}}}]