Question
Mathematics Question on matrix transformation
Consider a matrix A=αα2β+γββ2γ+αγγ2α+β
where α,β,γ are three distinct natural numbers.
If (α−β)16(β−γ)16(γ−α)16det(adj(adj(adj(adj A))))=232×316,
then the number of such 3-tuples (α,β,γ) is _________.
Answer
det(A)=αα2β+γββ2γ+αγγ2α+β
R3→R3+R1
⇒(α+β+γ)αα2\1ββ21γγ21
∴det(A)=(α+β+γ)(α–β)(β–γ)(γ–α)
Also, det (adj (adj (adj (adj (A)))))
=(det(A))24=(det(A))16
∴ (α−β)16(β−γ)16(γ−α)16(α+β+γ)16(α−β)16(β−γ)16(γ−α)16=(4.3)16
⇒α+β+γ=12
⇒(α,β,γ)distinct natural triplets
=11C2–1–3C2(4)=55–1–12 =42