Derivative of an inverse for Calc 1

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SUMMARY

The discussion focuses on finding the derivative of the inverse function, specifically (f−1)'(a) for the function f(x) = 5x^3 + 3x^2 + 5^x + 4, where a = 4. The correct approach involves using the formula d/dx(f-1) = 1/f '(f-1(x)), and participants clarify that instead of plugging in a value directly, one must solve the equation f(x) = 4 to find the corresponding x-value. The user initially calculated the derivative incorrectly by substituting values prematurely, leading to confusion in the solution process.

PREREQUISITES
  • Understanding of inverse functions and their derivatives
  • Familiarity with the chain rule in calculus
  • Knowledge of polynomial and exponential function differentiation
  • Ability to solve equations involving polynomials
NEXT STEPS
  • Study the application of the Inverse Function Theorem in calculus
  • Learn how to solve equations for specific function values, particularly for polynomials
  • Practice differentiation techniques for composite functions
  • Explore the implications of the chain rule in finding derivatives of inverse functions
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Students in introductory calculus courses, particularly those studying derivatives and inverse functions, as well as educators seeking to clarify these concepts for their students.

aero13
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Homework Statement


Find (f−1)'(a).
f(x) = 5x^3 + 3x^2 + 5^x + 4, a = 4

Homework Equations


I'm not entirely sure but I assume I have to use d/dx(f-1) = 1/f '(f-1(x))


The Attempt at a Solution


So far I switched y and x. Found dx/dy to be 15y^2 + 6y + 5. Then I switched dx/dy to dy/dx so the answer became 1/15^2 + 6y +5 and I plugged in 4 to get 1/269. But the answer is wrong
 
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No, do not plug in 4 solve the equation being equal to 4.
 
Ok so I set 1/15y^2 + 6y + 5 equal to 4. Ended up with 1 = 4(15y^2 + 6y + 5) so 1 = 60y^2 + 24y +20. Do I factor it from here?
 

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