1) (Chicone Ex. 1.76) Prove that a gradient system cannot have a periodic orbit. 2) (Chicone Ex 1.201) Prove that the system i=r-y-r, y=x+y=y, x,y R. has a unique periodic orbit that is globally attracting on R\ {0}. (This means that, for any { R, { 0, 0(t: ) converges to the periodic orbit.)