ExplainItLikeImFive 2 years ago Solve the equation. Identify any extraneous solutions.

1. ExplainItLikeImFive

2. ExplainItLikeImFive

A. 6 is a solution to the original equation. The value –5 is an extraneous solution. B. 6 and 5 are both extraneous solutions. C. 5 is a solution to the original equation. The value –6 is an extraneous solution. D. 6 and –5 are solutions.

3. dan815

do u know the meaning of extraneous

4. ExplainItLikeImFive

That it's unrelated, I think.

5. cwrw238

square both sides x^2 = x+ 30 x^2 -x - 30 = 0 can u solve this?

6. ExplainItLikeImFive

Ill try

7. cwrw238

extraneous means that although the working out gives it as a solution , it is not possible as a root

8. ExplainItLikeImFive

5 and 6?

9. cwrw238

not quite (x - 6)(x + 5) = 0 giving x = 6 , -5

10. ExplainItLikeImFive

So what do I do with that?

11. cwrw238

well see if these roots are possible by substituting each into the original equation

12. cwrw238

eg x = 6 6 = sqrt(6 + 30) 6 = 6 - so that is a genuine root

13. ExplainItLikeImFive

So I can eliminate B and C

14. cwrw238

yes

15. cwrw238

is -5 a solution?

16. ExplainItLikeImFive

I dont think so.

17. cwrw238

try plugging in -5 for x in the original equation

18. cwrw238

- 5 = sqrt (-5 + 30) does that work out?

19. ExplainItLikeImFive

No

20. cwrw238

what are the square roots of 25?

21. cwrw238

5 ANd -5 right?

22. ExplainItLikeImFive

Yes

23. cwrw238

so its a genuine root

24. ExplainItLikeImFive

So they're both genuine making them both solutions.

25. cwrw238

right

26. ExplainItLikeImFive

I do believe I'd pick D

27. cwrw238

correct

28. ExplainItLikeImFive

Thank you very much.

29. cwrw238

yw

30. Laaislima

wrong.

31. cwrw238

please explain why thats wrong

32. Laaislima

ask the teacher, I answered D and I got it wrong.

33. dan815

hii

34. dan815

|dw:1377219675010:dw|

35. dan815

is this your question?

36. dan815

oh sorry this is your question |dw:1377219778699:dw|

37. dan815

38. dan815

|dw:1377219879123:dw|

39. Laaislima

The right answer should be 6 is a solution to the original equation. The value –5 is an extraneous solution.