Question 640638
I'm assuming the system is really 


3x-4y+6z=1
9x+8y-12z=3
9x-4y+12z=4


Note: I'm going to be using |A| in place of D, |Ax| in place of Dx, |Ay| in place of Dy and |Az| in place of Dz.


*[invoke cramers_rule_3x3 3,-4,6,1,9,8,-12,3,9,-4,12,4]