First slide
System of linear equations
Question

Let α,β,γ be the real roots of the equation x3+ax2+bx+c=0(a,b,cR and a0) . If the system of equations (in u, v and w) given by  αu+βv+γw=0βu+γv+αw=0γu+αv+βw=0 has non-trivial solutions, then the value of a2/b is

Moderate
Solution

Equation x3+ax2+bx+c=0 has roots α,β,γ. Therefore,
α+β+γ=aαβ+βγ+γα=b
Since the given system of equations has non-trivial solutions,
we have

α0βγβγαγαβ=0 or α3+β3+γ33αβγ=0 or (α+β+γ)α2+β2+γ2αββγγα=0 or (α+β+γ)(α+β+γ)23(αβ+βγ+γα)=0aa23b=0  or  a2/b=3

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