Determining whether system of equations have a solution

[katerine]

how know how to do tis question
determine the value a
for which the resulting linear system has
i) no solution
ii)a unique solution
iii)infinitely many solution

x+y+z=3
x+2y+z=3
x+y+(a^2-8)z=a

 

[Fredrik]

x+y+z=3
x+2y+z=3

What do these two equations tell you about x,y and z?