g(x)=1-2x,f[g(x)]=1-x2/x2(不等于0)则f(1/2)=

问题描述:

g(x)=1-2x,f[g(x)]=1-x2/x2(不等于0)则f(1/2)=

f[g(x)
=(1-x^2)/x^2
令g(x)=1/2
1-2x=1/2
2x=1/2
x=1/4
f(1/2)=(1-x^2)/x^2
令x=1/4
有:
f(1/2)=(1-(1/4)^2)/(1/4)^2
=15