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Hessian determinant of a quadratic · formula reference

A positive determinant alone does not distinguish a local minimum from a maximum; inspect fₓₓ as well.

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Formula

A positive determinant alone does not distinguish a local minimum from a maximum; inspect fₓₓ as well.

det H = fₓₓ fᵧᵧ − fₓᵧ²

Worked example

For f(x,y) = 11x² + (-7)xy + 11y², calculate the determinant of its Hessian. Round the final result to 4 decimal places if needed.

H = [[22,-7],[-7,22]]. Take the product of its diagonal entries minus the product of its off-diagonal entries.

435

Prerequisites and checking

Algebra; calculus or linear algebra as appropriate to the topic. Keep units and rounding consistent. State the model conditions before applying the formula.

Further reading and review references

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