唔該....f.2既Factorize

2006-11-18 6:24 am

Factorize:
1). (x-3)² - 4x²

正確答案係 -3(x-1)(x+3)
但我要step,,我計唔到...唔該!!!

回答 (5)

2006-11-18 9:23 pm

✔ 最佳答案

(x-3)^2-4^2
=[(x-3)+2x][(x-3)-2x]
=(3x-3)(-x-3)
=-3(x-1)(x+3)
將前面的3和後面的(-)抽出，置於前面，就是答案。
前面3是common的數，後面的(-)是common的運算符號，兩者皆可抽出。

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2006-11-18 6:34 am

(x-3)² - 4x²

= x² - 6x + 9 - 4x²
= -3x² - 6x + 9
= -3( x² + 2x - 3)
= -3 ( x - 1 ) ( x + 3 )

參考: me

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2006-11-18 6:32 am

(x-3)^2-4x^2
=x² -6x+9-4x²
=-3x²-6x+9
=-3(x²+2x-3)
=-3(x+3)(x-1)

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2006-11-18 6:28 am

(x-3)² - 4x²
=x²-2(X)(3)+3²-4x²
=-3x²-6X+9
=-3(x²+2X-3)
=-3(x-1)(x+3)

參考: own knowledge

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2006-11-18 6:27 am

(x-3)² - 4x²
= (x-3)² - (2x)²
=(x-3+2x)(x-3-2x)
=(3x-3)(-x-3)
=-3(x-1)(x+3)

2006-11-17 22:28:32 補充：
a² - b² =(a-b)(a+b)

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