Multivariable Calc Absolute Extrema Problem

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SUMMARY

The discussion focuses on finding the absolute extrema of the function F(x,y) = sin(x)sin(y)sin(x+y) over the square defined by 0 ≤ x ≤ π and 0 ≤ y ≤ π. Participants emphasize the necessity of calculating the partial derivatives with respect to x and y, setting them to zero to identify critical points. The partial derivatives are derived as follows: ∂F/∂x = sin(y)[cos(x)sin(x+y) + sin(x)cos(x+y)] and ∂F/∂y = sin(x)[cos(y)sin(x+y) + sin(y)cos(x+y)]. The critical points identified include y = 0, π and x = 0, π, but further solutions remain unresolved.

PREREQUISITES
  • Understanding of multivariable calculus concepts, specifically partial derivatives.
  • Familiarity with the product rule in calculus.
  • Knowledge of trigonometric functions and their derivatives.
  • Ability to analyze critical points within a defined interval.
NEXT STEPS
  • Study the method for solving multivariable calculus problems involving absolute extrema.
  • Learn how to apply the second derivative test for functions of two variables.
  • Explore techniques for solving trigonometric equations within specified intervals.
  • Review examples of critical point analysis in multivariable functions.
USEFUL FOR

Students and educators in mathematics, particularly those studying multivariable calculus, as well as anyone seeking to understand optimization techniques for functions of two variables.

joemabloe
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Homework Statement


F(x,y)= sin(x)sin(y)sin(x+y) over the square 0\underline{}<x\underline{}<pi and 0\underline{}<y\underline{}<pi


(The values for x and y should be from 0 to pi INCLUSIVE)

Homework Equations





The Attempt at a Solution



I know I need to do the partial derivatives in terms of x and y and set them equal to 0 to find the critical points, but I am having some trouble with that.
 
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Do you know \frac{\partial}{\partial x}\sin(x), \frac{\partial}{\partial x}\sin(y) and \frac{\partial}{\partial x}\sin(x+y)? You can use the product rule to put them together- it works the same with partial derivatives. Then do the same but with \frac{\partial}{\partial y}.
 
Tomsk said:
Do you know \frac{\partial}{\partial x}\sin(x), \frac{\partial}{\partial x}\sin(y) and \frac{\partial}{\partial x}\sin(x+y)? You can use the product rule to put them together- it works the same with partial derivatives. Then do the same but with \frac{\partial}{\partial y}.


I already found that:

partial derivative in terms of x = siny[cosxsin(x+y)+sinxcos(x+y)]
you get y=0, pi because siny =0, but I don't know how to solve for the other solutions


partial derivative in terms of y = sinx[cosysin(x+y)+ sinycos(x+y)]
and you get x=0, pi because sinx=0

and then I have the same problem again and am stuck
 

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