f(x)+2f(1/x)=3x
f(1/x)+2f(x)=3/x→2f(1/x)+4f(x)=6/x
3f(x)=6/x-3x→f(x)=2/x-x→f(-x)=x-2/x
f(x)=f(-x)
2/x-x=x-2/x
x-2/x=0
x^2=2
x=±√2
f(x)+2f(1/x)=3x
f(1/x)+2f(x)=3/x→2f(1/x)+4f(x)=6/x
3f(x)=6/x-3x→f(x)=2/x-x→f(-x)=x-2/x
f(x)=f(-x)
2/x-x=x-2/x
x-2/x=0
x^2=2
x=±√2