## christinaxxx 2 years ago okay, so how do you factor 64x^3-8?

64=4^3 8=2^3 use$x^3-y^3=(x-y)(x^2+xy+y^2)$

2. christinaxxx

that doesn't exactly help me..

3. saifoo.khan

There's a formula for solving problems like these. @jonask wrote that formula above.

4. freewilly922

So for example $1000x^3 - 125y^3\to (10x)^3-(5y)^3$ Using SOAP $(10x-5y)((10x)^2+(10x)(5y)+(5y)^2)$ and then you clean up thingsl like 10x5y=50xy and stuff like that

5. christinaxxx

okay, the answer is 8(2x-1)(4x^2+2x+1). I'm not sure how to get that...

6. freewilly922

Were you able to apply the SOAP method to your problem? could you convert $64x^3\rightarrow ()^3$ ?

7. christinaxxx

yea, I got 64x^3-8=(4x)^3-2^3=(4x-2)(16x^2+8x+4). I don't know what to do from there

8. freewilly922

factor factor factor. 1) what # can you factor from (4x-2) ? 2) what # can you factor from (16x^2+8x+4)?

9. freewilly922

BTW, you did the SOAP correctly:)

10. christinaxxx

err....I'm not totally sure...

11. freewilly922

I'll do the first one and you can do the second. (4x+2) = 2(2x+1) since you can divide 4 and 2 by 2:)

12. freewilly922

What is the larges integer number that divides 16, 8, and 4?

13. christinaxxx

4, and then you multiply two and 4 and that's where the 8 comes from! I see!

14. freewilly922

Yay! Remember, next to perseverence (sp?), Factoring is probably the most important skill for math

15. christinaxxx

thank you!

16. timtimi

use polynomial division procedure:D