## anonymous 5 years ago need help finding the solution(s) to this equation..

1. anonymous

$y ^{-1}-22y ^{-1 \over 2}+120=0$

2. myininaya

let u=y^(-1/2)

3. myininaya

so what does u^2=?

4. anonymous

x?

5. myininaya

u^2=y^(-1)

6. anonymous

ok, thanks. so where do I go from here?

7. myininaya

do you know how to factor u^2-22u+120=0

8. anonymous

i'm trying to figure out what works for 22 and 120..does anything besides 2 go into them both?

9. myininaya

(u-10)(u-12)=0

10. anonymous

so will the 2 solutions be positive 10 and 12 then?

11. myininaya

y^(-1/2)=10 y^(-1/2)=12 since u=y^(-1/2)

12. myininaya

solve for y from both of these equations and you are done

13. anonymous

would it be 10 1/2 and 12 1/2 then? i didn't know the solutions could be anything besides a whole numbers

14. myininaya

y=10^(-2) y=12^(-2) you can evaluate those

15. anonymous

Sorry I have so many questions..I just want to make sure I understand completely. To evaluate these what exactly do i do?

16. myininaya

do you know law of exponents?

17. anonymous

possibly. I'm not sure exactly what that entails. I don't know the tnames for all these math terms

18. myininaya

y=10^(-2)=1/(10^2) y=12^(-2)=1/(12^2) can you evaluate it now?

19. anonymous

do they just end up being 10 and 12?

20. myininaya

y=1/(10*10) y=1/(12*12) can you evaluate these now?

21. anonymous

100 and 144?

22. anonymous

I just didn't think it would be that large of number.

23. myininaya

y=1/100 y=1/144

24. myininaya

you can plug these in to check if you want

25. anonymous

oh the 1 does stay on top? wasn't sure about that. Sorry i'm so incompetent at math.

26. anonymous

Ok will do. thanks

27. myininaya

np how about a medal? lol

28. anonymous

i'd say you earned it!

29. myininaya

yay! :)

30. myininaya

thanks you i will give you one too

31. anonymous

yay! Idk if i deserve one but thanks anyways! :)

32. myininaya

lol ok deserve it here if we have the function f(n)=2 find f(3)=...

33. anonymous

2..or n...er.. uhh

34. myininaya

lol thats right

35. anonymous

woohoo!

36. myininaya

the 2 is right

37. myininaya

its a horizontal line going through the y axis at 2 so no matter what you plug in fir x (or n) you will always get 2

38. myininaya

have a goodnight