## anonymous one year ago Graph of function f of x equals 2 to the power of negative x. Graph of function g of x equals 5 to the power of x. Graph of p of x is a line segment connecting points negative 1, negative 3 and 2, 12. Which function has all real numbers as its domain? Only f(x) Both g(x) and p(x) Both f(x) and g(x) Only p(x)

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1. anonymous

2. anonymous

@ali2x2

3. anonymous

@henrry123

4. anonymous

will give medal for right answer

5. geerky42

What do you think? Can you plug -2 in p(x)?

6. anonymous

yeah u can ? i think

7. geerky42

ok what is p(-2)?

8. anonymous

-2p

9. geerky42

Domain is basically "group" of x-coordinates. Do p(x) have value in x=-2 ?

10. geerky42

p(x) is function, not variable

11. anonymous

i am like very bad at math lol but i think it dont

12. geerky42

let's just say you have h(x) = x h(x) has domain of all real number because you can plug any values in h(x)

13. anonymous

okay

14. geerky42

You can see that p(x) only goes from about -1 to 2 in x-coordinate, right?

15. anonymous

yes i do

16. geerky42

|dw:1438987265095:dw|

17. anonymous

|dw:1438987281477:dw|

18. geerky42

yeah there are ends. So domain of p(x) is not all real number. Does that make sense?

19. anonymous

yes it do

20. geerky42

p(-3) is not definied (has no value) because -3 is not in domain of p(x)

21. geerky42

okay what about f(x) and g(x)?

22. geerky42

defined *

23. anonymous

|dw:1438987402176:dw|

24. geerky42

\(f(x) = 2^{-x}\) \(g(x)=5^x\) Is there any x value you cannot plug in?

25. anonymous

-2

26. anonymous

and 1 ?

27. geerky42

f(-2) has no value?

28. geerky42

well f(-2) = \(2^{-(-2)} = 2^2 = 4\) So -2 is in domain of f(x). same goes for g(x)

29. anonymous

okay i was right with the -2

30. geerky42

well domain is more than just -2.

31. geerky42

does f(10) have value? f(100)? f(1000)?

32. anonymous

100

33. geerky42

and not f(10) nor f(1000)?

34. geerky42

Looks like you don't understand how functions work.

35. anonymous

i dont

36. geerky42

you can think of it as "machine"|dw:1438987847196:dw| like f(x) would "change" -2 to any number, depend on what f(x) is. Make sense so far?

37. anonymous

okay i see what u mean

38. geerky42

domain is basically like what number you can put into machine

39. geerky42

if domain is 1 to 3, you can only put in any number between 1 to 3. No 5 or something

40. geerky42

If domain is real number, that means you can put in ANY (real) number.

41. anonymous

okay

42. geerky42

do you understand?

43. anonymous

so i can say any number

44. geerky42

well, can you plug any number in f(x) and g(x)? That's the question

45. anonymous

yes u can

46. geerky42

ok so domain of f(x) and g(x) is real number.

47. anonymous

yes

48. geerky42

49. geerky42

sorry for taking so long time lol

50. anonymous

thxs for trying to show me i really do want to learn math

51. geerky42