question_answer

Given that matrix . If \[xyz=60\] and \[8x+4y+3z=20,\] then A (adjA) is equal to

A)            

B)

C)

D)

Correct Answer: C

Solution :

[c] A adj \[A=\left| A \right|I\] \[\left| A \right|=xyz-8x-3(z-8)+2(2-2y)\] \[\left| A \right|=xyz-(8x+3z+4y)+28\] \[=60-20+28=68\] =