For what value of x will |adj A| =-20 if A = \(\begin{bmatrix}1 & 3\\2 & 2x \end{bmatrix}\)?
Answer & explanation
Correct answer: option 3
|adj A| = \( { |A| }^{ n-1 } \)
-20 = \( { |A| }^{ 2-1 } \)
-20 = |A|
-20= 2x-6
2x= -14
x=-7
For what value of x will |adj A| =-20 if A = \(\begin{bmatrix}1 & 3\\2 & 2x \end{bmatrix}\)?
Correct answer: option 3
|adj A| = \( { |A| }^{ n-1 } \)
-20 = \( { |A| }^{ 2-1 } \)
-20 = |A|
-20= 2x-6
2x= -14
x=-7