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Let A be an m n matrix with rank r. Suppose A = BU, where U is in echelon form. Show
Chapter 3, Problem 13(choose chapter or problem)
Let A be an m n matrix with rank r. Suppose A = BU, where U is in echelon form. Show that the first r columns of B give a basis for C(A). (In particular, if EA = U, where U is the echelon form of A and E is the product of elementary matrices by which we reduce A to U, then the first r columns of E 1 give a basis for C(A).)
Questions & Answers
QUESTION:
Let A be an m n matrix with rank r. Suppose A = BU, where U is in echelon form. Show that the first r columns of B give a basis for C(A). (In particular, if EA = U, where U is the echelon form of A and E is the product of elementary matrices by which we reduce A to U, then the first r columns of E 1 give a basis for C(A).)
ANSWER:Step 1 of 2
It is given that, is an matrix with rank .
And,
.
Also, is in echelon form.
It is known that,
If be a -dimensional subspace. Then any vectors that span must be linearly independent and any linearly independent vectors in must span .
To prove that, the first columns of give a basis for .