## Kathatesmath94 2 years ago I have a multiple choice question but my answer doesn't match my answer choices... Can someone tell me what i did wrong???

1. lilg132

yes show me what you've done and the question

2. Kathatesmath94

|dw:1354239603490:dw|

3. Kathatesmath94

thats the answer i chose but it says it is wrong.... my answer choices are: -5+18sqrt5 -5+38sqrt5 35+20sqrt5 35+10sqrt5--- the answer i chose and it says it is wrong... I am not sure why or what i did wrong can someone please help??

4. lilg132

the last bit is wrong its not -80 its -40

5. Kathatesmath94

oh that was -8sqrt5

6. lilg132

-5 + 18 sqrt 5

7. lilg132

that last bit is -8 sqrt 5?

8. lilg132

it shouldn't be it should be -40

9. Kathatesmath94

yeah cause it is 2sqrt5*4sqrt5

10. lilg132

yes that should give you - 40

11. Kathatesmath94

how did you get-40?? im a little confused

12. lilg132

5 * 4 = 20 * -2

13. lilg132

= -40

14. Kathatesmath94

where does the 5 come from? the sqrt?

15. lilg132

yes

16. Kathatesmath94

so you take one of the 5's from one of the sqrt and leave the other one?

17. lilg132

ok ignore the way i said let me try and explain the way you do it

18. lilg132

so we have -2 sqrt 5 * 4 sqrt 5

19. lilg132

-2 * 4 = -8

20. Kathatesmath94

im sorry I just want to make sure i understand where the 5 comes from

21. lilg132

sqrt 5 * sqrt 5 = 5

22. lilg132

so we multiply -8 * 5 = -40

23. lilg132

is that easier to understand?

24. Kathatesmath94

oh so the sqrt * the same swrt will just be the number??

25. lilg132

yes

26. Kathatesmath94

that makes perfect sense actually

27. lilg132

good :)

28. lilg132

29. Kathatesmath94

thank you soo much for explainging it and not just giving me the answer. if I have any other problem I will post them for sure. I really appreciate it

30. lilg132