## anonymous 5 years ago state the domain and range f(x)=2(1/3)^x

1. anonymous

domain all of real range is positive R

2. anonymous

howd you get that?

3. anonymous

all the possible values of x which satisfies the relation will give you the domain.. n for every x the outcome gives you the range

4. anonymous

Basically you're looking for disallowed values for x. If for example you had $$\sqrt{x}$$ for your function you would know that negative numbers for x are not allowed. If you had $$\frac{4}{x}$$ then 0 would not be allowed. If you had $$\sqrt{5-x}$$ then your domain would be numbers less than or equal to 5. etc

5. anonymous

shouldnt they be numbers?

6. anonymous

The domain and range are sets of numbers. There are many values you can plug in for x and get many different values for the function.

7. anonymous

so why is the domain and range not numbers?

8. anonymous

it is a set of numbers

9. anonymous

????

10. anonymous

you dont understand what is meant by a "set of numbers"??

11. anonymous

i just dont understand what your saying

12. anonymous

{1, 2, 3.4, 15} is a set of 4 numbers. (-5,1) is a set of infinitely many numbers between -5 and 1, but not including -5 or 1

13. anonymous

i get that!!! I just dont understand the domain and range

14. anonymous

Well the domain is just a set of numbers that are 'legal' to plug in for x.

15. anonymous

If your function is well behaved (doesn't divide or take the square root) then anything is legal. Otherwise you might have to restrict what x can be. If you divide by x, then x cannot be 0. If you divide by x+3 then x cannot be -3. If you take the square root of x, then x cannot be negative, etc.

16. anonymous

i dont get it

17. anonymous

Can you take the square root of a negative number?

18. anonymous

(and get a real result)

19. anonymous

I have to go, but we can talk about it another time if you like.

20. anonymous

margaret are you aware of complex numbers?

21. anonymous

no im not of complex numbers

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