WEBVTT

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Enter y equals negative two x squared plus twelve x plus five.

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The original window can hide the maximum.

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Open Graph Settings.

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Set the x minimum to zero and maximum to six, and the y minimum to zero and maximum to twenty five.

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This window includes the allowed input interval and the top of the parabola.

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Changing the viewing window does not restrict the equation itself.

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Keep the question’s domain in mind.

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Select the curve, then tap the vertex point.

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The displayed coordinates are three comma twenty three.

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Three is the input; twenty three is the maximum output.

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Completing the square gives negative two times x minus three squared, plus twenty three.

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A negative square cannot increase that value.

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The permitted interval contains three, and both endpoints give five.

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For a different interval, check its endpoints and whether the vertex is allowed.