Find the Big-Oh estimation of the following a. f(n)=(n-2)4+ n(n+3), f(n) = O(................) b. g(n)= n(n+1)(2n+3)/2, g(n) =O.............. c. k(n)= nlog( n +2n) + n(n+1), k(n)=O(.................. d. int f(int n) { if(n==0) return 3; else return n+f(n-1); run-time= O(..............) Compute the sum of the following sequences a. 2+4+8+..........+1024 = b. 2+4 +6+ 8 +..........+ 90 = c. En if(n) + II 3 g(n) ;f(n)= n+1,g(n)=n