4. (20 pts) Write true or false to each of the following statements. (i) If f(n) 0(n) and g(n) E (n), then f(n) + g(n) 89(n). (j) If f(n) E 0(n), then n1x f(n) E O(n3). (k) If f(n) O(n) and g(n) E O(n2), then f(n) x g(n) E O(n) (1) If f(n) E (n logn), then f(n) n o( ) 3 n-log n