立方和,立方差的公式證明
回答 (1)
2008-05-04 6:34 am
✔ 最佳答案
(a +b)^3= a^3+ 3a^2 *b + 3b^2* a + b^3(a +b)^3-3a^2* b- 3b^2* a = a^3+ b^3
(a +b)*((a b)^2-3ab)= a^3+ b^3
(a +b)(a^2-ab+ b^2) = a^3 +b^3
(a-b)^3= a^3-3a^2 *b + 3b^2* a -b^3
(a-b)^3 +3a^2* b- 3b^2* a = a^3-b^3
(a-b)*((a -b)^2+ 3ab)= a^3-b^3
(a-b)(a^2+ ab +b^2) = a^3-b^3
參考: me
收錄日期: 2021-04-16 12:16:48
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