申論題

 Consider the following linear system with its coefficient matrix A given right next to it. 

What is the basic feasible solution corresponding to the first four columns of A? That is, use the first four columns of A as the basis to find a basic feasible solution(求解A 的前四行所對應到 的基本可行解). **Note**: You must use linear algebra related mathematics to find your answer 求解必需使用與「線性代數相關」的數學計算,否則不予計分).