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AP EAMCET · Maths · Application of Derivatives

If the length of the sub-tangent at any point \(P\) on a curve is proportional to the abscissa of the point P. then the equation of that curve is ( C is an arbitrary constant)

  1. A \(y^k+x^k=C\)
  2. B \(x^{1 / k} C=y^k\)
  3. C \((x+y)^k=C\)
  4. D \(y=x^{1 / k} C\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(y=x^{1 / k} C\)

Step-by-step Solution

Detailed explanation

Length of sub-tangent \(=\frac{y}{\frac{d y}{d x}}\) According to question, \(\frac{y}{\frac{d y}{d x}}=k x \Rightarrow \frac{d x}{k x}=\frac{d y}{y}\) \(\Rightarrow \log y=\frac{1}{k} \log x+\log C \Rightarrow y=x^{1 / k} C\)