Question

如何求k/(k^2+1)^2的最大值?

Answer 1

分母乘开,上下同除以k

k/(k^2+1)^2=k/(k^2+2k+1)=1/(k+1/k+1)

令t=k+1/k

k+1/k>=2

所以原式=1/(1+t)=