How many solutions do the following equations have

2. How many solutions do the following equations have?
6y-2z = -12
-4x-3y+9z = 46
4x+3y-9z = -46

A none
B precisely one
C precisely two
D infinitely many

Since equation 2 may be wroten as 4x+3y-9z=-46 (amplify by (-1) both sides ) , the eq 2 is equal to eq3 .- This is named that they are " coupled" .- In this way, you have 3 variables and only 2 equations , eq 1 and eq 2 , so the system has infinitely solutions .- Answer D .-