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AP EAMCET · Maths · Quadratic Equation

If the roots of the equation \(x^3+3 p x^2+3 q x-8=0\) are in an arithmetic progression then \(2 p^3-3 p q=\)

  1. A 8
  2. B -8
  3. C 4
  4. D -4
Verified Solution

Answer & Solution

Correct Answer

(A) 8

Step-by-step Solution

Detailed explanation

\((a-d)+a+(a+d) = -3p \implies 3a = -3p \implies a = -p\) \((a-d)a(a+d) = -(-8) \implies a(a^2-d^2)=8\) \(-p((-p)^2-d^2)=8 \implies -p(p^2-d^2)=8 \implies -p^3+pd^2=8 \implies pd^2=p^3+8\) \((a-d)a+a(a+d)+(a-d)(a+d)=3q \implies 3a^2-d^2=3q\)…