Cho bài toán quy hoạch tuyến tính sau:  
 
 

1 2 3 4 5
1 2 3
2 3 4
2 5
1 ( ) 2 6 4 2 3 min
2 4 60
2 4 2 68
3 44
3 0; 1,5 j
g x x x x x x
x x x
x x x
x x
x j
     
    
   

  
 
a) Tìm bài toán đối ngẫu của bài toán trên.
b) Giải bài toán gốc bằng phƣơng pháp đơn hình rồi suy ra kết quả của bài toán đối
ngẫu.

Which situation can be modeled by the inequality 5 + 10w ≥ 45? a. you start with $5 and save $10 a week until you have at least $45. b. you start with 5 baseball cards and purchase 10 cards every week until you have at most 45 cards. c. you start with 5 water bottles and purchases cases of 10 water bottles each until you have a total of 45 water bottles. d. you spend $5 plus $10 per week until you have less than $45.

Which number completes the inequality? 2/3 < _ < 7/9

Over which interval is the graph of f(x) = x2 + 5x + 6 increasing?