2*2+1/2=9/2=2f(2)+f(1/2),18/2 = 4f(2) + 2f(1/2),2f(1/2)= 18/2 - 4f(2).
2*(1/2)+1/2=3/2=2f(1/2)+f(2)= 18/2 - 4f(2) + f(2) = 18/2 - 3f(2),
3f(2)=18/2 - 3/2 = 15/2,
f(2) = 5/2
2*2+1/2=9/2=2f(2)+f(1/2),18/2 = 4f(2) + 2f(1/2),2f(1/2)= 18/2 - 4f(2).
2*(1/2)+1/2=3/2=2f(1/2)+f(2)= 18/2 - 4f(2) + f(2) = 18/2 - 3f(2),
3f(2)=18/2 - 3/2 = 15/2,
f(2) = 5/2