If a,b,c are the sides of a Δ ABC such that x²-2(a+b+c)x +3Κ(ab+bc+ac)=0 has real roots then,

a) K <4/3

b) K>5/3

c) K ε ( 4/3,5/3)

the ans is  k<2/3

let a=b=c

option a==> let k=1 (<4/3),, the d=B²-4AC<0 not real

option b ===> let k=2 (>5/3) again d<0

option c ====> let k= 3/2  (={4/3+5/3}/2) again d<0

check options pls and approve