Understanding Partial Derivatives: Solving for f'(x) at a Specific Point

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SUMMARY

The discussion centers on finding the partial derivative of the function f(x,y) = x(x^2+y^2)^(-3/2)*e^(sin(x^2y)) at the point (1,0). The textbook solution simplifies the function by substituting y=0, resulting in f(x) = x^(-2) before differentiating to obtain the derivative value of -2. The confusion arises from the legality of substituting y into the function before differentiation, which is valid when treating y as a constant in the context of partial derivatives.

PREREQUISITES
  • Understanding of partial derivatives in multivariable calculus
  • Familiarity with the chain rule and product rule in differentiation
  • Knowledge of exponential functions and their derivatives
  • Basic concepts of limits and continuity in calculus
NEXT STEPS
  • Study the properties of partial derivatives and their applications in multivariable functions
  • Learn about the chain rule and product rule in the context of partial differentiation
  • Explore examples of differentiating functions with multiple variables
  • Investigate the implications of treating variables as constants in partial derivatives
USEFUL FOR

Students and educators in calculus, particularly those focusing on multivariable functions, as well as anyone seeking to deepen their understanding of partial derivatives and their applications.

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Homework Statement


If f(x,y) = x(x^2+y^2)^(-3/2)*e^(sin(x^2y)) find the derivative of f with respect to x at the point (1,0).


The Attempt at a Solution


The textbook solution just plugs 0 into y and gets f(x) = x^-2 and then proceeds to differentiate this resulting in the answer -2. I don't understand why this is legal. How can you just plug the point into the function and then take the derivative?

For example, if I had the function y = x and I wanted the derivative at x=0. You can't just plug in zero and take the derivative...?
 
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Because when you taking a partial derivative of a function of two variables f(x,y) with respect to x you assume y is a constant. You can either find it for any y or plug in a value for y to being with. y=x isn't a function of two variables.
 

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