I have to verify these games are convex-concave:
a) f(p,q)=-(pq)^2
b) f(p,q)= -(p^2-2p+1)(q^2+4q+5)
I am a bit confused as i thought i was supposed to take the second derivative with respect to p, show it is positive then take the second derivative with respect to q and show it is negative but i get that both of these are negative.
Thanks for any help