## Geometry_Hater 2 years ago How the heck do you expand 2x - y^7?

1. Geometry_Hater

(2x - y) ^7 i meant

2. Argos

Foil it out

3. precal

or use pascal's triangle

4. Geometry_Hater

i dont know how to use pascals triangle properly

5. Geometry_Hater

I dont know what numbers to use for it really.

6. precal

have you been shown pascal's triangle, this usually happens in algebra 2 or precal

7. precal

|dw:1357255357277:dw|

8. Geometry_Hater

yes i've seen the triangle but im unsure which row of numbers im using

9. precal

we need the 7th row 1 7 21 35 35 21 7 1

10. precal

|dw:1357255487760:dw|lets go back to one you know (x+y)^2

11. precal

|dw:1357255543811:dw|do you see the pattern?

12. Geometry_Hater

i see

13. precal

|dw:1357255613641:dw||dw:1357255598900:dw|

14. precal

notice what is happening to x x^2, x^1, x^0 notice what is happenting to y y^0, y^1, y^2

15. precal

we will use the same patter for your problem

16. Geometry_Hater

so the power of x goes down while the power of y goes up?

17. precal

yes

18. precal

|dw:1357255801781:dw|

19. precal

|dw:1357255969026:dw|

20. precal

|dw:1357256006811:dw|ok just simplify it now