Prove that if the roots of $10x^3-cx^2-54x-27$ are in HP then the roots of $27x^3+54x^2 +cx-10$ are in AP?

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I know we exchange $x$ by $\frac1x$ but how does that work? AP-arithmetic progression HP-harmonic progression

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Roots of second in AP => one of this roots is -54/27/3 ( r-d + r + r+d = -54/27) => you can calculate unique value of c

Great overkill :)