Not sure how to input matrices into latex but its an easy problem:
A=
|7 -4 -6 |
|2 0 -3 |
|1 2 -5 |
Evaluate |A| by expanding down the third column:
I get:
[-6(-1)^{4}(3)]+[-3(-1)^{5}(18)]+[-5(-1)^{6}(8)]
=-6(3)+3(18)-5(8)
=-4
answer is supposed to be -10, which i've arrived at expanding another row and column, what am I doing wrong?