Xiao-Ming University Games in this year's long jump competition in a satisfactory jump out of the fu

you can jump jump, when describing his center of gravity height change, he and then to focus on the maximum take-off when the time spent is about the number of .

Please write the specific process, thank you. Awards

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h =- 409t ² +7 / 2t

h =- 409 (t ² -7/818t +7 ² / 1636 ²) +409 * 7 ² / 1636 ²

h =- 409 (t-7 / 1636) ² +320656

when t = 7 / 1636, after his take-off to the highest center of gravity