## johnson32 Group Title 3x^2=7 one year ago one year ago

1. Lukecrayonz

3x=sqrt(7) x=sqrt(7)/3

2. johnson32

hi, i got the answer. not sure if anyone done math labs online, how do you input this

3. 03453660

|dw:1349872076838:dw|

4. Lukecrayonz

034 what in the world is wrong with your x's lol

5. johnson32

yes, i work this the same, however when inputing it online, coming back incorrect maybe the symbol

6. 03453660

@Lukecrayonz hahaha why???

7. Lukecrayonz

Looks like a 2pi or 2r or something :P

8. 03453660

what ever it looks like but its my habit

9. johnson32

help, how to write the correct solution set (4-3x)^2=39?

10. Lukecrayonz

Expand (4-3x)^2

11. johnson32

expand?

12. Frank1991

If you expand it you get: (4-3x)*(4-3x)=9x^2 -24x +16

13. Frank1991

and then = 9x^2 -24x +16 -39 =0=9x^2 -24x -23

14. Frank1991

and use the abc formula

15. Frank1991

16. Frank1991

I'm dutch, sorry

17. johnson32

@ Frank 1991yes I got what you where saying

18. johnson32

i see what you have here, and i have similar, I guess I need to simplify this because it does not show in my options in labs

19. johnson32

@Frank1991, i meant have to simplify all radicals. heck its multiply choice

20. johnson32

use the square root property to solve for the equation. (x-9)^2=64

21. Frank1991

in the last case you could say $\sqrt{(x-9)^{2}}=\sqrt{64}=8=x-9$

22. Frank1991

so x = 8+9

23. johnson32

@Frank1991, my answers are as yours, but when i type them in them in the computer labs they come back wrong.

24. Frank1991

oh that is strange you could check what wolframalpha is saying

25. johnson32

@Frank1991 sure thing

26. Frank1991

Yes wolfram alpha is also saying something different

27. Frank1991

I forgot about that a sqaure could also be negative

28. Frank1991

29. johnson32

yes

30. johnson32

@Frank1991 .. thanks

31. johnson32

The formula A=P (1+r)^2 gives the amount A in dollars that P dollars will grow to in 2 years interst rate r ( where r is given as a decimal), using compound intreset. What interest rate will cause $3000 to grow to$3370.80 in 2 years..

32. johnson32

The formula S=16t^2 is used to approximate the distance S, in feet, that an object falls freely from the rest in t seconds. The height of a building is 1048 feet. How long would it take for an object to fall from the top?

33. Frank1991

To the first question:3000=3370.8(1+r)^2 => 3000=3370.8 (r^2 +2r +1) => r^2 +2r +1 = 3000/3370.8 => r^2 +2r +(1-3000/3370.8) = 0 and solve this for r. Probably one of the answers is negative and that makes no sense

34. mayankdevnani

|dw:1349875404939:dw|

35. mayankdevnani

@johnson32 got it

36. Frank1991

second one: 1048=16 *t ^2 => t = squarroot( 1048/16) = ...

37. Frank1991

I hope it helped @johnson32

38. johnson32

@Frank1991 , so you got 0% interest rate,

39. johnson32

@mayankdevnani , yes thank you got that one solve already

40. mayankdevnani

ok

41. Frank1991

no r is the intrest rate

42. johnson32

@Frank1991 , I got 65.5 seconds for the object falling at

43. Frank1991

so use the quadratic formula for: r^2 +2r +(1-3000/3370.8) = 0 and r would be your answer

44. johnson32

got it

45. Frank1991

oh the 3000 and 3370.8 should switch

46. Frank1991

You obtain r = -2.06 or r=0.06

47. Frank1991

r=-2.06 makes no sense because there is an increase not a decrease, so your final answer is 0.06

48. Frank1991

got it? @johnson32

49. johnson32

yes I got it, thank you