... system (1 ), (2) are ( 0, 0 ), ( 0, 1 ), ( 0, −1 ), ( 1, 0)and (− 1, 0). One has f( 1, 0) = f(− 1, 0) = e−1and f has global maximumat the points ( 1, 0) and (− 1, 0). One has f( 0, 1) = f( 0, −1) = −e−1andf ... A−1. This proves part a). For part b) all bijare zero exceptb 1,1 = 2, bn,n= (−1)n , bi,i+1= bi+1,i= (−1)ifor i = 1, 2, . . . , n − 1.Problem 2. (13 points)Let f ∈ C1(a, b ), limx→a+f(x) ... =ni=1xπ(i)and A = { 1, 2, . . . , k} \ {π(i) : i = 1, 2, . . . , n}. Assume that (y, xr) > 0 for all r ∈ A. Theny,r∈Axr> 0and in view of y +r∈Axr= 0 one gets −(y, y) > 0, which...