Q.

If the set of all solutions of |x2+x–9|=|x|+|x2–9| is [α,β]∪[γ,∞), then (α2+β2+γ2) is equal to :          [2026]

1 9  
2 18  
3 36  
4 72  

Ans.

(2)

We have, |x2+x–9|=|x|+|x2–9|

If |a+b|=|a|+|b|, then a·b≥0

∴ x·(x2–9)≥0

⇒ x(x+3)(x–3)≥0

⇒ x∈[–3,0]∪[3,∞)

Hence, α=–3,β=0,γ=3

Thus, α2+β2+γ2=18