A.Aˉ¹ = I
[1 ... 1] x [a ... b] = [1 ... 0]
[X ... 1] .. [c ... d] ..[0 ... 1]
a + c = 1
aX + c = 0
b + d = 0
bX + d = 1
det(Aˉ¹) = 1/2
|a ... b| = 1/2
|c ... d|
ad - bc = 1/2
a + c = 1 ---> c = 1 - a
aX + c = 0
aX + 1 - a = 0
a = -1/(X - 1)
c = 1 - a
c = 1 + 1/(X - 1)
c = X/(X - 1)
b + d = 0
b = -d
bX + d = 1
-dX + d = 1 (.1)
dX - d = -1
d = -1/(X - 1)
b = -d
b = 1/(X - 1)
ad - bc = 1/2
[-1/(X - 1)].[-1/(X - 1)] - [1/(X - 1)].[X/(X - 1)] = 1/2
1/(X - 1)² - [X/(X - 1)²] = 1/2
(1 - X)/(X - 1)² = 1/2 .(-1)
(X - 1)/(X - 1)² = -1/2
1/(X - 1) = -1/2
-(X - 1) = 2
-X + 1 = 2
X = -1
Letra A