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AP EAMCET · Maths · Application of Derivatives

Find the equation of normal to the curve \(y=x^3-3 x\), which is parallel to the line \(2 x+18 y=9\) ?

  1. A \(x+9 y=20\) only
  2. B \(x+9 y=40\) only
  3. C \(x+9 y= \pm 20\)
  4. D \(x+9 y= \pm 40\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(x+9 y= \pm 20\)

Step-by-step Solution

Detailed explanation

Given, line is \(2 x+18 y=9\) \[ \begin{gathered} \text { slope }(m)=\frac{-a}{b} \\ m=\frac{-2}{18}=-\frac{1}{9} \end{gathered} \] Given equation of curve is \[ y=x^3-3 x \] Differentiate w.r.to ' \(x\) ', we get \[ \frac{d y}{d x}=3 x^2-3 \] \(\therefore\) Slope of normal…