## Emily778 Group Title check for extraneous solutions. sqrt x+7-x=1 Please show step by step on how to do this. Thankyou. 7 months ago 7 months ago

1. RolyPoly Group Title

Let $$u=\sqrt{x}$$, then x = $$u^2$$ Now, the equation becomes $u+7-u^2=1$ Can you do it?

2. Emily778 Group Title

Wat?

3. Emily778 Group Title

@Krazete

4. Emily778 Group Title

I don't get the way you're explaining it to me @RolyPoly

5. Krazete Group Title

Please make use of parentheses. The way you write problems is sorta confusing. Is it √(x+7)-x=1 or ...?

6. Emily778 Group Title

I guess. Sorry, it doesn't show parentheses on my math problem.

7. RolyPoly Group Title

Is the equation (1)$$\sqrt{ x+7-x} =1$$ or (2) $$\sqrt{x}+7-x=1$$?

8. Emily778 Group Title

nvm, i got the answer. Thx

9. Emily778 Group Title

nvm.. I tried wolframalpha. But only get two step by steps each day:(

10. Emily778 Group Title

I'll have to get the answer tomorrow.

11. RolyPoly Group Title

It would be better if you know how to solve it, instead of just relying on WolframAlpha.

12. Emily778 Group Title

eh, true. But lets be honest with ourselves, I'm never going to use this advanced of math in the future.

13. Emily778 Group Title

Honestly, I just need credits/passed classes

14. Emily778 Group Title

you can argue all you want, but it's true.

15. RolyPoly Group Title

Don't want to argue, just want to help you pass the course and you can learn how to solve it at the same time :)

16. Emily778 Group Title

can you just show me please? I'm 18 lessons behind:(

17. nikato Group Title

$\sqrt{x+7}-x=1$

18. nikato Group Title

add x to both sides

19. Emily778 Group Title

It would be a different story if I wasn't that behind

20. RolyPoly Group Title

$\sqrt{x-7-x}=1$$\sqrt{x-7}-x=1$$\sqrt{x}-7-x=1$ Which one is your question?

21. Emily778 Group Title

like this @nikato |dw:1388896983931:dw|

22. Emily778 Group Title

the 2nd one @RolyPoly

23. nikato Group Title

yup

24. Emily778 Group Title

what next?

25. nikato Group Title

so now u have|dw:1388897108757:dw| now square both sides

26. Emily778 Group Title

i know 9 is the solution

27. Emily778 Group Title

what next?

28. nikato Group Title

did u square both sides. and simplified it?

29. Emily778 Group Title

how do I simplify it?

30. nikato Group Title

|dw:1388897450469:dw|does that make sense?

31. Emily778 Group Title

yeah.

32. Emily778 Group Title

what next?

33. nikato Group Title

subtract x and 7 on both sides so that the equation equal 0

34. nikato Group Title

|dw:1388897691356:dw|

35. Emily778 Group Title

what next? :D ha

36. nikato Group Title

|dw:1388897800670:dw| can u factor the right side?

37. Emily778 Group Title

can you show me? eheh

38. nikato Group Title

|dw:1388898386363:dw|

39. Emily778 Group Title

9?

40. Emily778 Group Title

@nikato

41. Emily778 Group Title

it has to be 9.

42. nikato Group Title

no, i dont think 9 is a solution. try pluggin it back into the origianl equation. it doesnt work

43. nikato Group Title

|dw:1388899069611:dw|

44. Emily778 Group Title

then you did it wrong. Ugh. Wolfram said it was 9

45. nikato Group Title

no, im for sure 9 is not an answer. it doesnt make sense. its one fo those^

46. Emily778 Group Title

@Krazete is he wrong or not?

47. Emily778 Group Title

sorry, nikato. I gotta make sure.

48. nikato Group Title

yea, its fine. whatever u feel is right

49. Krazete Group Title

nikato's right.

50. Emily778 Group Title

okayy,, it's just wolfram said the solution was 9. But I guess it's better to have something than nothing at all.

51. nikato Group Title

maybe u typed in the wrong equation in wolfrma

52. Krazete Group Title

Look at what Wolfram says under "input." Is it the same as your problem? It might've calculated √x instead of √(x+7). Parentheses are quite important.

53. Emily778 Group Title

nikato, what do I do next? Sorry for doubting you

54. nikato Group Title

|dw:1388899779946:dw| solve for x. did most of the work. should be easy for u. there are suppose to be 2 answers

55. Emily778 Group Title

one of them is 2.

56. nikato Group Title

yes. and the other?

57. Emily778 Group Title

o?

58. nikato Group Title

no, -3. so now u want to find if there is anyextraneous answers

59. nikato Group Title

plug both back into the equation and see if they make sense|dw:1388900195738:dw|

60. Emily778 Group Title

ugh. How much more is there??

61. Emily778 Group Title

what next?

62. nikato Group Title

no, this is it. check if both of those equation are true. if they are not, then that "x" is extraneous

63. Emily778 Group Title

it's 1.

64. Emily778 Group Title

thanks. :p

65. nikato Group Title

WAIT NO. its either 2 or -3. i helped plug in both in for x the first one is x=2 and the other is x=-3

66. Emily778 Group Title

I did it in my calculator. How'd you get your answer?

67. nikato Group Title

no, thats not what i meant

68. nikato Group Title

|dw:1388901004098:dw|

69. Emily778 Group Title

I'm sorry, I still don't get how you got those answers. I got -5 and 1. 1 was correct. -5 was incorrect.

70. nikato Group Title

yes. so that means -3 is the extraneous answer. remember how we worked the problem, and got 2 and -3 as the naswer. however when u plug -3 back into the original equation u get -5 instead of 1. which means the answer doesnt "work" which we call an extraneous answer

71. Emily778 Group Title

so what is the answer???

72. nikato Group Title

just 2

73. nikato Group Title

becuz like i said ^ -3 is an extraneous solution

74. Emily778 Group Title

so, I would put "x=2 only"?

75. nikato Group Title

yup