A function satisfies $f(x)+2f(1/x)=3x$ for every non-zero $x$. The value of $f$(2) is:

Putting $x=2$ gives $f(2)+2f(1/2)=6$; putting $x=1/2$ gives $f(1/2)+2f(2)=3/2$. From the second, $f(1/2)=3/2-2f(2)$; substituting into the first gives $f(2)+3-4f(2)=6$, so $-3f(2)=3$ and $f(2)=-1$. (Answering 3 uses only the first equation and treats $f$ as if $f(2)=f(1/2)$.) Check: $f(1/2)=7/2$, and $-1+2(7/2)=6$ while $7/2+2(-1)=3/2$.