A) \[a+b+c=0\]
B) \[{{a}^{-1}}+{{b}^{-1}}+{{c}^{-1}}=0\]
C) \[a=b=c\]
D) None of these
Correct Answer: B
Solution :
[b] For \[n=-(l+m)\], the second relation gives \[a{{l}^{2}}+b{{m}^{2}}+c{{(l+m)}^{2}}=0\] or \[(a+c){{l}^{2}}+2clm+(b+c){{m}^{2}}=0.\] For parallel lines, the two roots must be equal \[\Rightarrow 4{{c}^{2}}-4(b+c)(a+c)=0\Rightarrow ab+bc+ca=0\]You need to login to perform this action.
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