## christinaxxx Group Title okay, so how do you factor 64x^3-8? one year ago one year ago

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

2. christinaxxx Group Title

that doesn't exactly help me..

3. saifoo.khan Group Title

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

4. freewilly922 Group Title

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 Group Title

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

6. freewilly922 Group Title

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

7. christinaxxx Group Title

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 Group Title

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

9. freewilly922 Group Title

BTW, you did the SOAP correctly:)

10. christinaxxx Group Title

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

11. freewilly922 Group Title

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 Group Title

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

13. christinaxxx Group Title

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

14. freewilly922 Group Title

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

15. christinaxxx Group Title

thank you!

16. timtimi Group Title

use polynomial division procedure:D