Diketahui matriks A = (-5 3 -2 1), B = (1 -1 1 -3),
Invers matriks AB adalah ...
A. (½ -2 -½ 1)
B. (-½ -2 ½ 1)
C. (2 ½ -1 -½)
D. (2 -½ -1 ½)
E. (1 ½ 2 -½)
Pembahasan
AB = ⎧-5 3⎫⎧1 -1⎫ = ⎧-2 -4⎫
⎩-2 1⎭⎩1 -3⎭ ⎩-1 -1⎭
(AB)⁻¹ = 1 ⎧-1 4⎫
(-2)(-1) – (-4)(-1)⎩1 -2⎭
= 1 ⎧-1 4⎫
-2⎩1 -2⎭
= ⎧½ -2⎫
⎩-½ 1⎭
Jawaban: A