Answer:
Answer B: -30
Step-by-step explanation:
Let B be as follows:
[-18 3]
[4 1 ]
To find the determinant, multiply diagonally downward from -18 through 1, obtaining -18. We keep this sign as is.
Continue: Start at 4 and move diagonally upward through 3; this product is 12. Because we moved upward, give this result the opposite sign: -12.
Now add together these two products; that is, add together -18 and -12. Here the sum is -30. This is the determinant of the matrix. It's Answer B.
Finding the determinant of a 3x3 matrix obviously requires more steps, but the general approach is similar.
