Generally, the function y=log(a)x,

When a is greater than 1, it is monotone increasing function and convex; When a is less than 1 and greater than 0, the function is monotonically decreasing and concave.

The general form of exponential function is y = a x(a >；; 0 and ≠ 1)

(x∈r)，

If a is greater than 1, the exponential function increases monotonically; A is less than 1 greater than 0, which decreases monotonously.

[f(g(x))]'=f'(g(x))*g'(x)

( 1/( 1+x^2))*2x+a=0,2x+a( 1+x^2)=0

x=(-2+√4-4a^2)/2a,- 1≤a≤ 1