

InterviewSolution
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If α and β are the roots of the quadratic equation ax2 + bx + c = 0, such that β = α1/3, then(a) (a3b)1/4 + (ac3)1/4 + a = 0(b) (a3c)1/4 + (ac3)1/4 + b = 0(c) (a3b)1/4 + (ab3)1/4 + c = 0(d) (a3c)1/4 + (bc3)1/4 + a = 0 |
Answer» (b) (ac3)1/4 + (a3c)1/4 + b = 0 Let α, β be the roots of the equation ax2 + bx + c = 0. Then, α + β = \(-\frac{b}{a}\) .....(i) αβ = \(\frac{c}{a}\) ......(ii) and β = α1/3 .......(iii) ∴ From (ii) and (iii), α. (α)1/3 = \(\frac{c}{a}\) ⇒ α4/3 = \(\frac{c}{a}\) ⇒ α = \(\bigg(\frac{c}{a}\bigg)^{3/4}\) ∴ β = \(\bigg(\big(\frac{c}{a}\big)^{3/4}\bigg)^{1/3}\) = \(\bigg(\frac{c}{a}\bigg)^{1/4}\) ∴ Putting these values of a and b in eqn. (i), we have \(\bigg(\frac{c}{a}\bigg)^{3/4}\) + (c/a)1/4 = \(-\frac{b}{a}\) ⇒ a. a–3/4 c3/4 + a. a–1/4 c1/4 = – b ⇒ a1/4 c3/4 + a3/4 c1/4 + b = 0 ⇒ (ac3)1/4 + (a3c)1/4 + b = 0. |
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