## lizz123 one year ago Medal @freckles Perform the operations using adding and subtracting polynomials.

1. lizz123

$7x - [2\left( x ^{2} -z\right) + 4x ^{2} -7z] + 6z ^{2}$

2. freckles

ok so let's do any distributing needed a(b+c)=ab+ac

3. freckles

let's begin with the 2(x^2-z) thing

4. freckles

can apply the distributive property there

5. freckles

$2(x^2-z) \\ \text{ here we are just going \to multiply the two terms inside the ( ) \by 2 } \\ 2(x^2)-2(z)=2x^2-2z$

6. freckles

so now you have $7x-[2x^2-2z+4x^2-7z]+6z^2$

7. freckles

you have one more area to apply distributive property

8. freckles

do you see the - in front of the [ ]?

9. freckles

drop the [ ] and just change the sign to each term inside the [ ] this is the same as multiplying by -1

10. freckles

I will let you try this part

11. lizz123

So, $7x - [ (2x^{2} -2z)+4x ^{2} -7z] +6$

12. lizz123

$7x + [ -2x ^{2}+2z -4x ^{2}+7z]+6$

13. freckles

yep

14. freckles

now combine like terms

15. freckles

$+7x\\ -2x^2-4x^2=? \\ 2z+7z=? \\+ 6$

16. lizz123

|dw:1434404812374:dw|

17. freckles

|dw:1434404949777:dw| that is the only term I have a problem with

18. lizz123

|dw:1434404992422:dw|

19. freckles

but notice I also circled the + in front of the 4x^2

20. freckles

that should be a -2x^2-4x^2 which is -6x^2

21. lizz123

how come

22. freckles

how come there is a - in front of 4x^2?

23. freckles

or how come -2-4 is -6?

24. freckles

earlier you had written this: $7x + [ -2x ^{2}+2z -4x ^{2}+7z]+6$ there is a - in front of 2x^2 and a - in front of 4x^2

25. freckles

-(2+4)=-(6)=-6

26. freckles

so -2x^2-4x^2=-6x^2

27. lizz123

oh yeah

28. lizz123

i get it. Thank you very much. I really appreciate it.

29. freckles

|dw:1434405199854:dw|

30. freckles

good job though on the other terms :)