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AP EAMCET · Maths · Quadratic Equation

The value of \(4 x^3-4 x^2-7 x+127\) when \(x=\frac{4+5 \sqrt{-1}}{2}\) is

  1. A \(1\)
  2. B \(2\)
  3. C \(3\)
  4. D \(4\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(4\)

Step-by-step Solution

Detailed explanation

\(\because x=\frac{4+5 \sqrt{-1}}{2} \Rightarrow 2 x=4+5 \sqrt{-1}\) ...(i) \((2 x)^2=(4+5 \sqrt{-1})^2\) \(\Rightarrow 4 x^2=16-25+40 \sqrt{-1}\) \(\Rightarrow 4 x^2=-9+40 \sqrt{-1}\) ...(ii) Equation (ii) \(-8 \times\) (i) \(4 x^2-16 x=-41 \Rightarrow 4 x^2-16 x+41=0\)…