Given,
For the system of linear equations
2x−y+3z=5
3x+2y−z=7
4x+5y+αz=β,
Now finding,
D=∣234−1253−1α∣
⇒D=2(2α+5)+(3α+4)+3(7)
⇒D=7α+35
Now we know that, for unique solutionD=0⇒α=–5
So, in option (B) α=–6 corresponds to infinitely many solution, which is completely wrong hence, this is answer.