MathCastle
Linear AlgebraSuperchallengeRow Reduction & Rank

Row Reduction & Rank · Superchallenge problem

Let AA be the 4×84\times 8 matrix with entries aij=j i−1a_{ij} = j^{\,i-1} for 1≤i≤41 \le i \le 4, 1≤j≤81 \le j \le 8; its rows are (1,1,…,1)(1, 1, \ldots, 1), (1,2,…,8)(1, 2, \ldots, 8), (1,4,…,64)(1, 4, \ldots, 64) and (1,8,…,512)(1, 8, \ldots, 512). Find the sum of the eight entries in the first row of the reduced row echelon form of AA.