1.
The value of aa for which the system of equations
a3x+(a+1)3y+(a+2)3z=0a^3x + (a+1)^3y + (a+2)^3z = 0

ax+(a+1)y+(a+2)z=0ax + (a+1)y + (a+2)z = 0

x+y+z=0x + y + z = 0

has a non-zero solution is