Matrices and Determinants

We find D=0 & since no pair of planes are parallel, so there are infinite number of solution s.
Let αP1+λP2=P3
⇒P1+7P2=13P3
⇒b1+7b2=13b3
A) D≠0⇒ unique solution for any b1,b2,b3
B) D=0 but P1+7P2≠13P3
C) D=0 Also b2=−2b1,b3=−b1 but b1+7b2=13b3 hence two simultaneous equations in b1,b2,b3 can be considered as two different planes hence line of intersection has only common solutions other solutions are not common hence C is Not Correct
D) D≠0