Question:

If $x = \sqrt{2^{cosec^{-1} } t}$ and $y = \sqrt{2^{\sec^{-1}} t} (|t | \geq 1)$, then $\frac{dy}{dx}$ is equal to :

Updated On: Sep 12, 2024
  • $\frac{y}{x}$
  • $\frac{x}{y}$
  • $ - \frac{y}{x}$
  • $ - \frac{x}{y}$
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The Correct Option is C

Solution and Explanation

Given: $x=\sqrt{2^{\text {cose }^{-1} t}}$ and $y=\sqrt{2^{\text {sec }^{-1} t}}(|t| \geq 1)$
Now, $\frac{d y}{d x}=\frac{d y / d t}{d x / d t}$
$=\frac{\frac{1}{2 \sqrt{2 \sec ^{-1} t}} 2^{\sec ^{-1} t} \ln \left(\frac{1}{t \sqrt{t^{2}-1}}\right)}{-\frac{1}{2 \sqrt{2 cosec^{-1} t}} 2^{\text {cosec }^{-1}} \ln \left(\frac{1}{t \sqrt{t^{2}-1}}\right)} $
$=-\frac{\sqrt{2^{ ec ^{-1} t}}}{\sqrt{2^{\text {omee }^{-1} y}}}=\frac{-y}{x}$
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Concepts Used:

Continuity

A function is said to be continuous at a point x = a,  if

limx→a

f(x) Exists, and

limx→a

f(x) = f(a)

It implies that if the left hand limit (L.H.L), right hand limit (R.H.L) and the value of the function at x=a exists and these parameters are equal to each other, then the function f is said to be continuous at x=a.

If the function is undefined or does not exist, then we say that the function is discontinuous.

Conditions for continuity of a function: For any function to be continuous, it must meet the following conditions:

  • The function f(x) specified at x = a, is continuous only if f(a) belongs to real number.
  • The limit of the function as x approaches a, exists.
  • The limit of the function as x approaches a, must be equal to the function value at x = a.