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- #1

why are these statements not correct ?

1. If A and B are invertible, then

[tex]a\cdot (B^{-1}A^{-1}B)^{^{t}}[/tex]

is not necessarily invertible

2. If A and B are invertible, then

[tex]a\cdot (A+B)[/tex]

is not necessarily invertible, but if it is, it's inverse is the matrix

[tex]\frac{1}{a}\cdot (A^{-1}+B^{-1})[/tex]

Thanks...