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问题: 分解因式...立方和and立方差....By-熊

1.(x+y)^3+8

2. 0.128a^3-b^3/4

3. 2y^3m-1/32

4. (1/8)x^3-(1/729)y^3

5. (a^2+1/a^2)^2-4

6. a^3+3a^2b+3ab^2+b^3-c^3

7. x^2-(50/7)x+1

8. y^3-(8/3)y^3-1

9. x^2-(2/15)x-1/15

10. x^2-x+6/25

11. 17-(6x^2+5)

12. 20y^2+y-1

13. a^3+x^3+3x^2+3x+1

14. x^4-5x^2+4

题目比较多哈...不过希望有主要的过程..

解答:

1.(x+y)^3+8 =(x+y)^3+2^3=(x+y+2)[(x+y)^2-2(x+y)+4]
2. 0.128a^3-b^3/4 =4/1000[2^3*4^3a^3-(10b)^3]
=(1/5)^3(8a-10b)(64a^2+80b+100b^2)
3. 2y^3m-1/32 =2(y^3-1/64)=2[y^3-(1/4)^3]

4.(1/8)x^3-(1/729)y^3 =1/2)^3X^3-1/9^3Y^3=(1/2X)^3-(1/9Y)^3
5. (a^2+1/a^2)^2-4 =(a^2+1/a^2+2)(a^2+1/a^2-2)
=(a+1/a)^2(a-1/a)^2=[(a+1/a)(a-1/a)]^2
6. a^3+3a^2b+3ab^2+b^3-c^3 =(a+b)^3-c^3
=(a+b-c)[(a+b)^2+c(a+b)+c^2]