整數指數律;續多項式的因式分解

2008-04-27 11:16 pm
34. (3.6*10^9+4*10^8)^-1
Ans: 2.5*10^-10
24. 16x^2-8xy+3/4 y^2
Ans: 1/4(8x-y)(8x-3y)
30. 2p^6-128
Ans: 2(p+2)(p^2-2p+4)(p-2)(p^2+2p+4)

回答 (1)

2008-04-27 11:28 pm
✔ 最佳答案
34. (3.6*10^9 4*10^8)^-1
=(36*10^8 4*10^8)^-1
=(40*10^8)^-1
=(0.4*10^10)^-1
=(1/0.4*10^-10)
=2.5*10^-10

24. 16x^2-8xy 3/4 y^2
=(1/4) (64x^2-32xy 3 y^2)
=(1/4)(8x-y)(8x-3y)

30. 2p^6-128
= 2 (p^6-64)
= 2 ((p^3)^2-8^2)
= 2 (p^3 8)(p^3-8)
= 2 (p 2)(p^2-2p 4)(p-2)(p^2-2p 4)
這一題要用公式
a^2-b^2=(a b)(a-b)
a^3-b^3=(a-b)(a^2 ab b^2) 及
a^3 b^3=(a b)(a^2-ab b^2)

2008-04-27 15:31:35 補充:
不知為何,有些加號不見了。
34.=(36*10^8+4*10^8)^-1
=(40*10^8)^-1
=(0.4*10^10)^-1
=(1/0.4*10^-10)
=2.5*10^-10

24. 16x^2-8xy+3/4 y^2
=(1/4) (64x^2-32xy+3 y^2)
=(1/4)(8x-y)(8x-3y)

30. 2p^6-128
= 2 (p^6-64)
= 2 ((p^3)^2-8^2)
= 2 (p^3+8)(p^3-8)
= 2 (p+2)(p^2-2p+4)(p-2)(p^2-2p+4)


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