factorise: 3a^2-12b^2?

2009-12-23 4:15 pm

i got 3(a^2-4b^2) but i didnt get full marks for this. how can you factorise this more? thanks x

回答 (5)

2009-12-23 4:22 pm

✔ 最佳答案

a^2 - b^2 = (a + b)(a - b)

3a^2 - 12b^2
= 3(a^2 - 4b^2)
= 3[a^2 - (2b)^2]
= 3(a + 2b)(a - 2b)

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2009-12-23 4:21 pm

Continue with difference of squares
3(a - 2b)(a + 2b)

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2009-12-23 4:37 pm

3a^2 - 12b^2
= 3 (a^2 - 4b^2)

=3[(a)^2 - (2b)^2]

=3[(a + 2b)(a-2b)]

=(3)(a + 2b)(a - 2b)

參考: me

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2009-12-23 4:24 pm

3 ( aÂ² - 4 bÂ² )

3 ( a - 2b ) ( a + 2b )

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2009-12-23 4:21 pm

You need to factor the a²-4b² using the difference of square formula as well.

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