For the system of linear equations \( \alpha x+y+z=1, \ x+\alpha y+z=1, \ x+y+\alpha z=\beta \), which one of the following statements is NOT correct?
It has infinitely many solutions if \( \alpha=2 \) and \( \beta=-1 \)
It has infinitely many solutions if \( \alpha=1 \) and \( \beta=1 \)
It has no solution if \( \alpha=-2 \) and \( \beta=1 \)
\( x+y+z=\frac{3}{4} \) if \( \alpha=2 \) and \( \beta=1 \)