## roselin Group Title whats the lim x goes to infinity of 2/square root of x one year ago one year ago

1. JoãoVitorMC Group Title

0

2. roselin Group Title

yes

3. zepdrix Group Title

Rose if you're not convinced, just plug a large number into your calculator to check! :) if you plug one bajillion in for x, what value do you get for the limit? $\frac{ 2 }{ \sqrt{bajillion} }\approx \frac{ 2 }{ 999999999 } \approx 0$

4. JoãoVitorMC Group Title

yeah, but do what zepdrix said only for check, because if you do this in a test for example, it will be wrong because infinity is NOT a number...

5. roselin Group Title

okay

6. roselin Group Title

it is always 0 ?

7. JoãoVitorMC Group Title

no! it will depends on what you are taking the limit, always try to simplify the limit, try to do not have a denominator, in this case we can not simplify so we do this

8. roselin Group Title

i am trying to solve this problem where x goes to infinity 2+square root of x/ 2- square root of x

9. roselin Group Title

i am getting the answer as 1, is it right?

10. JoãoVitorMC Group Title

$\lim_{x \rightarrow \infty}\frac{2+\sqrt{x}}{2-\sqrt{x}}$

11. JoãoVitorMC Group Title

this one?

12. roselin Group Title

yes,

13. JoãoVitorMC Group Title

the limit is equal to -1

14. JoãoVitorMC Group Title

have you already study L'hospital rule ?

15. roselin Group Title

can you please explain how you got -1?

16. roselin Group Title

No,

17. JoãoVitorMC Group Title

ok let me explain

18. JoãoVitorMC Group Title

|dw:1350703643878:dw|

19. JoãoVitorMC Group Title

got it?

20. roselin Group Title

what did you do with the whole numerator thing? u ended up with X

21. JoãoVitorMC Group Title

when x goes to infinity, the other terms with lower power we take them off, and stay only with the higher terms them simply if possible and aply the limit

22. JoãoVitorMC Group Title

i will post how i got the numerator

23. roselin Group Title

ohh , u mean the limit of 4 and 4 sqrt x = 0?

24. JoãoVitorMC Group Title

|dw:1350704041192:dw|

25. JoãoVitorMC Group Title

no this i simply take them out because comparing with infinity they make no difference

26. roselin Group Title

oh okay,

27. JoãoVitorMC Group Title

when you deal with limits on the infinity you can make this assumptions

28. JoãoVitorMC Group Title

but take care...

29. JoãoVitorMC Group Title

when you see L'hostpital's Rule this limits will became very easy to solve.... you will see

30. roselin Group Title

we have not gotten to that yet.

31. JoãoVitorMC Group Title

yeah

32. roselin Group Title

if you do not mind then, I have one more problem. would you explain that one?

33. JoãoVitorMC Group Title

sure

34. roselin Group Title

thank you

35. roselin Group Title

lim sec x x goes to( -pi/2)^+

36. JoãoVitorMC Group Title

let me solve here one moment

37. roselin Group Title

okay

38. JoãoVitorMC Group Title

it is equal to infinity, i will draw here

39. roselin Group Title

okay

40. JoãoVitorMC Group Title

|dw:1350704691784:dw|

41. JoãoVitorMC Group Title

is it clear?

42. roselin Group Title

yes,viewing it.

43. JoãoVitorMC Group Title

see, when we have something divide by a number really really really small them it becomes a really really really large number so the limit tends to the infinity

44. roselin Group Title

okay, but how did you get that 10?

45. JoãoVitorMC Group Title

it is just a notation for this: 0.00000000000000000000000...00000000000001, then we represent this really small or large number with 10 power

46. roselin Group Title

oh ,okay. got it.

47. roselin Group Title

wait,wait

48. roselin Group Title

that (-pi/2)^+ is the same as (-pi/2)?

49. JoãoVitorMC Group Title

ALMOST the same, when we have this + is a little more than pi/2

50. JoãoVitorMC Group Title

-pi/2, sorry

51. roselin Group Title

so, the asnwer will be the same one right?

52. roselin Group Title

53. JoãoVitorMC Group Title

no, because if we take 1/0 it is not allowed. But 1/0.00000000001 is allowed

54. JoãoVitorMC Group Title

we can not divide by 0, NEVER

55. roselin Group Title

yes,that is true.

56. JoãoVitorMC Group Title

so you got it?

57. roselin Group Title

yeah.

58. roselin Group Title

Thank you soooo much.

59. JoãoVitorMC Group Title

yw :)

60. roselin Group Title

good night, byee

61. JoãoVitorMC Group Title

good, bye