Question 333 of 472MediumMCQ
If \[A = \left[ {(2−4−31) } \right]\],
then adj(3A2 + 12A) is equal to Solutions · 1
Official solution
We have, \[A = \left[ {(2−4−31) } \right]\]
\[ \therefore \] A2 = A.A = \[\left[ {(2−4−31) } \right]\left[ {(2−4−31) } \right]\]
= \[\left[ {(4+12−8−4−6−312+1) } \right]\]
= \[\left[ {(16−12−913) } \right]\]
Now, 3A2 + 12A
= \[3\left[ {(16−12−913) } \right] + 12\left[ {(2−4−31) } \right]\]
= \[\left[ {(48−36−2739) } \right] + \left[ {(24−48−3612) } \right]\]
= \[\left[ {(72−84−6351) } \right]\]
\[ \therefore \] adj(3A2 + 12A) = \[\left[ {(51846372) } \right]\] Answer the question to unlock