- #1
annoymage
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Homework Statement
Show that it is false
If A is invertible and A-1 = adj A, then det A= 1
Homework Equations
N/A
The Attempt at a Solution
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A is invertible iff A-1A = I
implies det(A-1A) = det(I)
implies det(A-1)det(A) = 1
implies det(A) = 1 or -1--------------------------------this is wrong, just ignore this part (edited)
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AND
A-1 = adj(A)
which is false because
A-1 = [tex]\frac{1}{det(A)}[/tex] adj(A)
so, which means the premise is already false
false implies (true or false)
is a true statement
so, is it the question wrong, or i did any mistake?
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