CAT Exam Model Paper 2 with solutions for free online practice

Putting x = $\frac{1}{\mathit{y}}$ ,we get
$27{\mathit{y}}^3+54{\mathit{y}}^2+\mathit{c}\mathit{y}-10=0$...(i)
This above eq. (i) must be in AP.
Let the roots of equation in y be
α − β, α, α + β (∵ roots are in AP)
∴ Σα = α − β + α + α + β = 3α
⇒ 3α = $-\frac{54}{27}$
⇒ α = $-\frac{2}{3}$
Now, α = $-\frac{2}{3}$ will satisfy the eq. (i), we get
$27\times \frac{-8}{27}+54\times \frac{4}{9}-\frac{2\mathit{c}}{3}-10=0$
$\mathit{c}=9$