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Grade 11Differential Calculus

find the value of d/dx[sin^-1 ((3x-2)-(x^3 /2)) and the other question,
siny+e^-cosy =e then dy/dx at (1,pi) is equal to ?

Profile image of Samarth Akula
8 Years agoGrade 11
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1 Answer

Profile image of Anish Singhal
7 Years ago

Let's tackle each part of your question step by step, starting with the derivative of the inverse sine function and then moving on to implicit differentiation for the second part.

Finding the Derivative of sin-1(3x - 2 - (x3/2))

To find the derivative of the function \( y = \sin^{-1}(3x - 2 - (x^3/2)) \), we will use the chain rule. The derivative of \( \sin^{-1}(u) \) with respect to \( x \) is given by:

  • dy/dx = 1 / √(1 - u²) * du/dx

Here, \( u = 3x - 2 - (x^3/2) \). Now, let's calculate \( du/dx \):

First, differentiate \( u \):

  • du/dx = d/dx[3x] - d/dx[2] - d/dx[(x^3/2)]
  • du/dx = 3 - 0 - (3/2)x²
  • du/dx = 3 - (3/2)x²

Next, we need to find \( 1 - u² \):

  • u = 3x - 2 - (x^3/2)
  • u² = (3x - 2 - (x^3/2))²

This expression can be complex, but we can find \( dy/dx \) directly:

Now, substituting back into our derivative formula:

  • dy/dx = 1 / √(1 - (3x - 2 - (x^3/2))²) * (3 - (3/2)x²)

And that gives us the derivative of the first function!

Applying Implicit Differentiation

Now, let's examine the second equation: \( \sin(y) + e^{-\cos(y)} = e \). We need to find \( dy/dx \) at the point (1, π).

To differentiate this equation implicitly with respect to \( x \), we apply the chain rule:

  • d/dx[sin(y)] + d/dx[e^{-cos(y)}] = d/dx[e]

Using the chain rule:

  • cos(y) * (dy/dx) + e^{-cos(y)} * sin(y) * (dy/dx) = 0

This can be rearranged to isolate \( dy/dx \):

  • (cos(y) + e^{-cos(y)} * sin(y)) * (dy/dx) = 0

So we have:

  • dy/dx = -1 * (e^{-cos(y)} * sin(y)) / cos(y)

Now, we need to evaluate this at the point (1, π):

  • Substituting y = π:
  • cos(π) = -1, sin(π) = 0.

So, at the point (1, π):

  • dy/dx = -1 * (e^{1} * 0) / (-1) = 0.

This means that the value of \( dy/dx \) at the point (1, π) is equal to 0.

Summary

To summarize:

  • The derivative of \( \sin^{-1}(3x - 2 - (x^3/2)) \) is given by a more complex expression involving the chain rule.
  • The value of \( dy/dx \) for the equation \( \sin(y) + e^{-\cos(y)} = e \) at the point (1, π) is 0.

Feel free to ask if you need further clarification on any of these steps or concepts!