## anonymous one year ago Two different plants grow each year at different rates, which are represented by the functions f(x) = 4x and g(x) = 5x + 2. What is the first year the f(x) height is greater than the g(x) height? A. Year 0 B.Year 1 C.Year 2 D.Year 3 Can i get some help plz

1. anonymous

@ali2x2

2. anonymous

@Michele_Laino can u help me plz

3. Michele_Laino

you have to substitute x=0, 1,2,3 then you have to compare the values f(x) and g(x) for each year. For example, if x=0, then we have: f(0) = 4*0 =0, and g(0)= 5*0+2=2, so f(0) < g(0) now, please do the same for other values of x

4. anonymous

so pu 4 in for f in the problem and 5 in for g

5. anonymous

u there

6. Michele_Laino

yes!

7. Michele_Laino

question: are f(x) and g(x) heights or rates?

8. anonymous

rates

9. Michele_Laino

so, are you familiar with differential calculus?

10. anonymous

no i am not ?

11. Michele_Laino

if f(x) is a rate, then the corresponding height h, is given solving this differential equation: $\Large \frac{{dh}}{{dx}} = 4x$

12. anonymous

ok i am trying to understand what is going on but for my first answer i put B. am i right

13. Michele_Laino

I'm pondering...

14. anonymous

okay

15. Michele_Laino

my reasoning is: height h1 for f(x) is: $\Large {h_1}\left( x \right) = 2{x^2}$ whereas height h2 for g(x) is: $\Large {h_2}\left( x \right) = \frac{{5{x^2}}}{2} + 2x$ and we have h2>h1, if x>0, whereas h2=h1 if x=0

16. Michele_Laino

17. anonymous

so A

18. Michele_Laino

19. Michele_Laino

20. anonymous

so what i need to do

21. Astrophysics

This doesn't really make sense, are the functions $f(x)=4x~~and~~g(x) = 5x+2~~~~or~~~~f(x)=4^x~~~~and~~~g(x) = 5x+2$

22. anonymous

Two different plants grow each year at different rates, which are represented by the functions f(x) = 4x and g(x) = 5x + 2. What is the first year the f(x) height is greater than the g(x) height? this is the problem

23. Astrophysics

What are the functions...from what i showed you

24. Astrophysics

is it to the power of x or just times x...

25. anonymous

just times

26. Astrophysics

So it's $f(x) = 4x$ and $g(x) = 5x+2$

27. anonymous

i am so confused tho

28. Astrophysics

Can you please take an image of your question and post it

29. anonymous

i dont know how to do thatfrom computer

30. anonymous

Two different plants grow each year at different rates, which are represented by the functions f(x) = 4x and g(x) = 5x + 2. What is the first year the f(x) height is greater than the g(x) height? Year 0 Year 1 Year 2 Year 3

31. Astrophysics

Ok all I am asking you is, what are the functions they gave you in the problem f(x), if it's to the power of x or is just 4x...

32. Astrophysics

and same for g(x)

33. Astrophysics

|dw:1438873919146:dw|

34. anonymous

Two different plants grow each year at different rates, which are represented by the functions f(x) = 4x and g(x) = 5x + 2 What is the first year the f(x) height is greater than the g(x) height? Year 0 Year 1 Year 2 Year 3

35. Astrophysics

cmon dude lol

36. anonymous

lol tbh i dont know

37. Astrophysics

38. Astrophysics

not how to do it

39. anonymous

lol o....

40. Astrophysics

Two different plants grow each year at different rates, which are represented by the functions f(x) = 4x and g(x) = 5x + 2 What is the first year the f(x) height is greater than the g(x) height?

41. Astrophysics

Are those to the power of x or just being multiplied by x

42. anonymous

being multiplied

43. Astrophysics

So it's exactly $f(x) = 4x~~~~~g(x) = 5x+2$ like that right?

44. anonymous

yes that right

45. Astrophysics

Ok well...then you can make a graph check this out |dw:1438874246367:dw| blue is g(x) and green is f(x)

46. anonymous

what am i looking for in the picture

47. Astrophysics

This doesn't make sense

48. Astrophysics

This shows g(x) > f(x) always

49. anonymous

ok so make a graph

50. Astrophysics

51. anonymous

how can u screen shot from computer

52. anonymous

did u get it

53. Astrophysics

not yet

54. Astrophysics

Ok I got it and it was to the power of x, I KNEW IT!! haha|dw:1438875745626:dw|

55. anonymous

lol okay

56. Astrophysics

Ok so now we can put in values as Michele did above, to see so let x = 0 $f(0) = 4^0 = 1$ $g(0) = 5(0)+2=2$ So its not year 0

57. anonymous

its 2

58. anonymous

C.

59. Astrophysics

$f(1) = 4^1=4$ $g(1) = 5(1)+2=7$ year 1 $f(2) = 4^2 = 16~~~~g(2) = 5(2)+2 = 12$

60. Astrophysics

Yup year 2 lol

61. Astrophysics

Bleh, that took so long xD, I knew something was fishy

62. anonymous

lol okay thx for your time

63. anonymous

Which of the following exponential functions goes through the points (1, 6) and (2, 12)? f(x) = 3(2)x f(x) = 2(3)x f(x) = 3(2)−x f(x) = 2(3)−x

64. anonymous

help me with this @Astrophysics

65. Astrophysics

Lol no problem

66. Astrophysics