解
F(x)在x=0处连续
x→0,1/sinx~1/x
lim(1+f(x)/x)^1/sinx
=lim(1+f(x)/x)^1/x
=lim(1+f(x)/x)^x/f(x)*f(x)/x*1/x
=e^limf(x)/x^2
=e^2
所以limf(x)/x^2=2
不理解请追问
解:
x→0,lim[1+f(x)/x]^(1/sinx)=e²
x→0,lim[1+f(x)/x]^(1/x)=e²
x→0,lim[1+f(x)/x]^(1/x)=e²
又x→0,lim[1+√x]^(1/x)=e²
所以f(x)/x=√x
得f(x)=x√x
故x→0,limf(x)/x²=lim(x√x)/x²=lim1/√x=∞
答案:∞