香港寵物小精靈村落 論壇

標題: 不懂兩題因式分解 [打印本頁]

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作者: ccshong28    時間: 11/10/2007 10:36 PM
標題: 不懂兩題因式分解
Fatorise the following.

3(a-b)+3(b-a)c^4

x^2-(y-z)^2
偶唔知點做

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作者: sapphire    時間: 11/10/2007 11:20 PM
Remember that x^2-y^2=(x+y)(x-y)

3(a-b)+3(b-a)c^4
=3(a-b)-3c^4(a-b)
=3(a-b)(1-c^4)
=3(a-b)(1+c^2)(1-c^2)  
=3(a-b)(1+c^2)(1+c)(1-c)

now u should know how to do the 2nd question, try to finish it urself
ans=(x+y-z)(x-y+z)

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