若正整数x,y满足x2-y2=64,则这样的正整数对(x,y)的个数是(  )

学习 时间:2026-04-07 18:28:36 阅读:9330
若正整数x,y满足x2-y2=64,则这样的正整数对(x,y)的个数是(  )A. 1B. 2C. 3D. 4

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2026-04-07 18:28:36

∵x2-y2=(x+y)(x-y),64=32×2=16×4,∴x+y=32x−y=2或x+y=16x−y=4,解得x=17y=15或x=10y=6.∴满足条件的正整数对(x,y)的个数是2.故选B.

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  • 陶醉的朋友
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    2026-04-07 18:28:36

    ∵x2-y2=(x+y)(x-y),64=32×2=16×4,∴x+y=32x−y=2或x+y=16x−y=4,解得x=17y=15或x=10y=6.∴满足条件的正整数对(x,y)的个数是2.故选B.

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