I NEED HELP PLEASE Find matrix A whose first column is a1 1

I NEED HELP PLEASE

Find matrix A whose first column is a_1 = [-1 2 1], third column is a_3 = [2 -1 -2], and reduced row echelon form is R = [1 3 0 1 3 0 0 1 3 2 0 0 0 0 0]

Solution

It is apparent from the RREF of A that the 2^nd column of A is a₂ = 3a₁ = 3(-1,2,1)^T = (-3,6, 3)^T , its 4^th column is a₄ = a₁ +3a₃ = (-1,2,1)^T + 3 (2,-1,-2)^T = (-1,2,1)^T + (6,-3,-6)^T = (5,-1,-5)^T and its 5^th column is a₅ = 3a₁+2a₃ = 3(-1,2,1)^T +2(2,-1,-2)^T = (-3,6,3)^T +(4,-2,-4)^T = (1,4,-1)^T. Therefore, A =

-1

-3

2

-1

1

2

6

-1

2

4

1

3

-2

1

-1

-1	-3	2	-1	1
2	6	-1	2	4
1	3	-2	1	-1