| 7(19) |
| 送交者: zhf 2019月11月13日20:11:27 於 [靈機一動] 發送悄悄話 |
| 回 答: 趣味的數學-162 由 gugeren 於 2019-11-12 19:21:35 |
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x^3 - y^3 = 10(x - y) (x^3 - y^3)/(x - y) = 10 x^2 + xy + y^2 = 10 (1) x^3 + y^3 = 16(x + y) (x^3 + y^3)/(x + y) = 16 x^2 - xy + y^2 = 16 (2) (2)+(1) 得 x^2 + y^2 = 13 (2)-(1) 得 -2xy = 6 (x-y)^2= 19 (x+y)^2= 7 (x^2 - y^2)^2 = 7(19) |
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