23-10-09 straight lines

If α,β and γ are the real roots of the equation x3 – 3px2 + 3qx – 1 = 0, then the centroid of the triangle with vertices (α,1/α) , (β,1/β) and (γ,1/γ) is:

I guess one of the easier QOD's

5 Answers

39
Dr.House ·

centroid= [ (α+β+γ)/3, Σ (αβ/3αβγ)]

α+β+γ=3p

Σαβ=3q

αβγ=1

so centroid is [p,q]

3
msp ·

put x=1/x in the given eqn we will get the eqn whose roots are 1/α,1/β,1/γ

so find the sum of roots of the two eqn helps to solve the problem.

62
Lokesh Verma ·

could someone express what bhargav has given in a even simpler way?

3
msp ·

sir din get.do u want us to have a simpler soln than bargav,

62
Lokesh Verma ·

I mean it wont be of much materila difference.. the result will be the same but was just wondering if someone could post of "different" logic for finding 1/a+1/b+1/c

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