F.2 maths (identities)

2010-11-10 6:52 am

要步驟+ans 唔該.
3(-9h-2k)(2k-9h)

回答 (3)

2010-11-11 4:14 am

✔ 最佳答案

3(-9h-2k)(2k-9h)
= -3 (2k-9h) (2k-9h)
= -3 [ (2k)^2 - (9h)^2 ]
= -3 (4k^2 - 81h^2)

2010-11-10 20:15:44 補充：
= -3 (4k^2 - 81h^2)
= 243h^2 - 12k^2

參考: girl, 漏左少少野

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2010-11-11 12:18 am

3(-9h-2k)(2k-9h)
-3(2k+9h)(2k-9h)
-3((2k)^2-(9h)^2)
-3(4k^2-81k^2)
-12k^2+243k^2
______________

2010-11-10 16:19:16 補充：
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參考: , 魔龍帝齊格益力多

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2010-11-10 6:54 am

3(-9h-2k)(2k-9h)
=(-27h-6k)(2k-9h)
=-54hk+243h²-12k²+54hk
=243h²-12k²

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