2 Answers
1357Δ1=Δ2=Δ3=0
Δ=-(a+b+c)(a2+b2+c2-ab-bc-ca)
a)Δ=0 and a=b=c
represent identical planes
b)Δ=0 and a+b+c=0, the planes pass through the same line of intersection
c)Δ≠0, unique solution (0,0,0)
d)a=b=c, a+b+c=0, a=b=c=0, so any point will satisfy this eqn
