数学规律题,比如50()58()56()54,怎么做呢,求指教!
2个回答
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把50,(x),58,(y),56,(z),54看成高阶等差数列,反复求差:
差:x-50,108-x,x+y-108,164-x-y,x+y+z-164,218-x-y-z,
差:......158-2x,2x+y-216,272-2x-2y,2x+2y+z-328,382-2x-2y-2z,
差:...............4x+y-374,488-4x-3y,4x+4y+z-600,710-4x-4y-3z,
令4x+y-374=488-4x-3y=4x+4y+z-600=710-4x-4y-3z,
整理得8x+4y=862,①
8x+7y+z=1088,②
8x+8y+4z=1310,③
②-①,3y+z=226,
③-②,y+3z=222.
解得y=57,z=55,
代入①,x=79.25
差:x-50,108-x,x+y-108,164-x-y,x+y+z-164,218-x-y-z,
差:......158-2x,2x+y-216,272-2x-2y,2x+2y+z-328,382-2x-2y-2z,
差:...............4x+y-374,488-4x-3y,4x+4y+z-600,710-4x-4y-3z,
令4x+y-374=488-4x-3y=4x+4y+z-600=710-4x-4y-3z,
整理得8x+4y=862,①
8x+7y+z=1088,②
8x+8y+4z=1310,③
②-①,3y+z=226,
③-②,y+3z=222.
解得y=57,z=55,
代入①,x=79.25
追问
咱能告诉结果不😂
追答
已算出x,y,z.
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