## mike12 2 years ago 6(x^3-64)

1. eyust707

simplify?

2. mike12

how

3. Callisto

Do you need to factorize it or expand it?

4. mike12

factorize

5. Callisto

Use \(a^3 - b^3 = (a-b)(a^2+ab+b^2)\)

6. Callisto

FYI, 64=4^3

7. abb0t

I believe the answer is: \[6x^3+384\]

8. mike12

i started off with 6x^3 +384

9. joyap03

distribution :) sir abbot is right

10. Callisto

Factorize.. not expand..

11. Callisto

And if you started from 6x^3 +384, you shouldn't get 6(x^3-64)...

12. mike12

i got 6(x^3-64)

13. Callisto

What is the original question?

14. mike12

factor 6x^3-384

15. Silenthill

= 6x^3-384 or 6(x-4)(x^2+4x+16)

16. Callisto

@mike12 Then you did right. 6x^3-384 = 6(x^3 - 64) Note that 64 can be written as 4^3, so you get = 6(x^3 - 4^3) Next apply the identity \(a^3-b^3 = (a-b)(a^2+ab+b^2)\) to factorize x^3 - 4^3. Can you do it?

17. mike12

ill try

18. mike12

give me a second

19. Callisto

Take your time :)

20. mike12

lol yeah im pretty lost

21. Callisto

Where?

22. mike12

applying the identity

23. Callisto

Have you learnt that identity yet?

24. mike12

yeah but actually trying to sub it in...having troubles

25. Callisto

What troubles? Can you show your work?

26. mike12

honestly just plugging in the equation... i dont know what to plug in or where

27. Callisto

Compare \(x^3 - 4^3 \) and \(a^3-b^3\) Can you identify what is a and b?

28. mike12

yeah

29. Callisto

What are they then?

30. Callisto

@mike12 What are a and b...???