设g(x)=ln(√(x^2+1)+x),g(-x)=ln(√(x^2+1)-x)=ln(1/(√(x^2+1)+x))=-ln(√(x^2+1)+x)=-g(x)
故g(x)为奇函数,g(2)=-g(-2)
由题 f(2)=ag(2)+8b+2=5
则 f(-2)=ag(-2)-8b+2=-ag(2)-8b+2=-(ag(2)+8b+2)+4=-f(2)+4=-5+4=-1