math 數學 Factor Trinomials

2012-11-12 11:07 pm
Factor the following trinomials.

1) a^2-7ab-120b^2

2) 4(3x-y)^2+21(3x-y)+5

3) 15a^5+15a^3b^3-90ab^4

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回答 (2)

2012-11-13 12:19 am
✔ 最佳答案
1) a^2-7ab-120b^2
=(a-15b)(a+8b)

2) 4(3x-y)^2+21(3x-y)+5
=[4(3x-y)+1][(3x-y)+5]
=(12x-4y+1)(3x-y+5)

3) 15a^5+15a^3b^3-90ab^4
=5(3a^5+5a^3b^3-18ab^4)
參考: ME
2012-11-14 11:08 am
Question 3:
中間的 term , +15a^3b^3, 有沒有打錯?
如果沒有打錯, 應該是
15a^5+15a^3b^3-90ab^4
15a (a^4 + a^2b^3 - 6b^4)


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