Question
If α,β are non real numbers satisfying x3−1=0 then the value of ∣∣
∣∣λ+1αβαλ+β1β1λ+α∣∣
∣∣ is equal to
∣∣λ+1αβαλ+β1β1λ+α∣∣
∣∣ is equal to
Answer: Option B
:
B
x3−1=0∴x=1,ω,ω2
Here, α=ω,β=ω2∣∣
∣
∣∣λ+1ωω2ωλ+ω21ω21λ+ω∣∣
∣
∣∣
Applying C1→C1+C2+C3, then
∣∣
∣
∣∣λωω2λλ+ω21λ1λ+ω∣∣
∣
∣∣
Applying R−2→R2−R1 and R3→R3−R1, then we get
∣∣
∣
∣∣λωω20λ+ω2−ω1−ω201−ωλ+ω−ω2∣∣
∣
∣∣=λ((λ+ω2−ω)(λ+ω−ω2)−(1−ω)(1−ω2))=λ(λ2)=λ3
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:
B
x3−1=0∴x=1,ω,ω2
Here, α=ω,β=ω2∣∣
∣
∣∣λ+1ωω2ωλ+ω21ω21λ+ω∣∣
∣
∣∣
Applying C1→C1+C2+C3, then
∣∣
∣
∣∣λωω2λλ+ω21λ1λ+ω∣∣
∣
∣∣
Applying R−2→R2−R1 and R3→R3−R1, then we get
∣∣
∣
∣∣λωω20λ+ω2−ω1−ω201−ωλ+ω−ω2∣∣
∣
∣∣=λ((λ+ω2−ω)(λ+ω−ω2)−(1−ω)(1−ω2))=λ(λ2)=λ3
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