Monday

October 20, 2014

October 20, 2014

Posted by **mathstudent** on Monday, December 4, 2006 at 5:25pm.

If AB = I,

prove BA = I

Presumably you have to do this without using the usual properties of the inverse of matrices. But we do need to use that if there exists a matrix B such that

A B = I

then the equation A X = 0 has the unique solution:

X = 0

So, let's start with:

AB = I

Multiply both sides by A on the right:

(AB)A = A

Now you use that (AB)A = A(BA) and you can rewrite the above equation as:

A(BA - I) = 0

And it follows that

BA = I

well if u decmial the 7 to a 6 good luck with that ..........

**Answer this Question**

**Related Questions**

linear algebra - if: A and B are matrices and A^2 is similar to B^2 Is A ...

matrices - Two matrices can be multiplied only if their sizes are compatible. ...

Matrices (math) - 0.433= (45.6*A) + (3.152*B) 0.3363= (11.92*A) + (37.675*B) ...

Math (matrices) - No one answered my matrix question. Let me rephrase: Let A, B...

Math - I have a few questions about T-Matrix. In excel, I am suppose to work ...

Urgent please help! matrices - solve using matrices x+3y-3z=12 3x-y+4z=0 -x+2y-z...

Algebra II - Can a matrix have a two digit number? I have to add the matrices[3 ...

MATH! - The Mountain Trail Resort sold 64 condominiums last year, all 1, 2, or 3...

MATH! - The Mountain Trail Resort sold 64 condominiums last year, all 1, 2, or 3...

Math - The Mountain Trail Resort sold 64 condominiums last year, all 1, 2, or 3 ...