Math Problem Statement
the equation, f(x, y) = x^2 - 3y + 30. Hessian Matrix: H(x, y) = \being{bmatrix} f_{xx} & f_{xy}\ f_{yx} & f_{yy}\end{bmatrix. If H(x, y) < 0, saddle point, H(x, y) > 0, turning point, if it is a turning point, if f_{xx} > 0, miminumum tunring point, f_{xx} < 0, maximum turning point. Identify each turning point of the equation.
Solution
The equation needs to be analyzed for its turning points, minimum, maximum, or saddle points using the Hessian matrix. Let’s follow the steps systematically:
1. First-Order Partial Derivatives
The first-order partial derivatives are:
The critical points occur where and : 2x = 0 \quad \Rightarrow \quad x = 0, \quad -3 = 0 \quad \Rightarrow \quad \text{No solution for y}. Thus, the function has no critical points because is constant and cannot equal zero.
2. Second-Order Partial Derivatives (Hessian Matrix Components)
The second-order partial derivatives are:
f_{yy} = \frac{\partial^2 f}{\partial y^2} = 0, \quad f_{xy} = f_{yx} = 0.$$ The Hessian matrix is: $$H(x, y) = \begin{bmatrix} f_{xx} & f_{xy} \\ f_{yx} & f_{yy} \end{bmatrix} = \begin{bmatrix} 2 & 0 \\ 0 & 0 \end{bmatrix}.$$ ### 3. Determinant of the Hessian The determinant of $$H(x, y)$$ is: $$\text{det}(H) = f_{xx}f_{yy} - (f_{xy})^2 = (2)(0) - (0)^2 = 0.$$ ### 4. Analysis of the Results - Since $$\text{det}(H) = 0$$, the Hessian test is inconclusive. This implies the nature of the point is indeterminate using only the Hessian determinant. - However, based on $$f_{xx} = 2 > 0$$, the function is convex in the $$x$$-direction, and no critical points satisfy both $$f_x = 0$$ and $$f_y = 0$$. Thus, we cannot identify a specific turning point. ### Conclusion The function $$f(x, y) = x^2 - 3y + 30$$ has **no critical points**. The absence of critical points precludes the identification of a minimum, maximum, or saddle point. --- Would you like further clarification or a deeper dive into the theoretical aspects? Here are some follow-up questions: 1. How is the determinant of the Hessian matrix related to the classification of critical points? 2. Why does the constant term $$-3y$$ prevent the existence of critical points in this case? 3. Can you provide another example where a Hessian determinant test is inconclusive? 4. How would the analysis change if $$f_y$$ were a function of $$y$$ instead of constant? 5. What does the convexity in the $$x$$-direction imply about the surface? **Tip:** If the Hessian determinant is zero, check the function's behavior in the region around the potential critical point for additional insights.Ask a new question for Free
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Math Problem Analysis
Mathematical Concepts
Multivariable Calculus
Hessian Matrix
Critical Points Analysis
Formulas
First-order partial derivatives: f_x = ∂f/∂x, f_y = ∂f/∂y
Second-order partial derivatives: f_{xx} = ∂^2f/∂x^2, f_{yy} = ∂^2f/∂y^2, f_{xy} = f_{yx} = ∂^2f/∂x∂y
Hessian determinant: det(H) = f_{xx}f_{yy} - (f_{xy})^2
Theorems
Hessian determinant test for classifying critical points
Suitable Grade Level
Grades 11-12 or early college
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