# Math Help - invertible matrices

1. ## invertible matrices

Show that if AB is invertible, so is A.

(there is a matrix w so that ABW=I.. why?)

2. Originally Posted by cottekr
Show that if AB is invertible, so is A.

(there is a matrix w so that ABW=I.. why?)

If AB is invertible there exists a matrix W s.t. (AB)W = I. But matrix multiplication is associative, so I = (AB)W = A(BW)...

Tonio

3. Originally Posted by cottekr
Show that if AB is invertible, so is A.

(there is a matrix w so that ABW=I.. why?)
That is, pretty much, the definition of "invertible", isn't it?