# I need help with homework

1. Sep 17, 2009

### Biaach

Hi im an 8th grader i gotta do my homework lol help me fast plz!
How do you do a problem like this??
2 -2
--
3

2. Sep 17, 2009

### Biaach

so what this question is 2 over 3 with a negetive exponent. sorry about that/

3. Sep 17, 2009

### symbolipoint

Your question is not precise. Try either good typesetting or use clear text-based notation; otherwise express clearly in writing what help you want.

How is the exponent applied? Is it applied to the entire fraction or is it applied just to the numerator?

4. Sep 17, 2009

### Biaach

it is only applied in the numerator.
2 over 3 with an negative exponent next to the 2.
How the heck do you do this :(
oh and the negetive exponent is -2.

5. Sep 17, 2009

### Integral

Staff Emeritus
Note that I have moved your post.

Not sure what your number is. Do you mean:

$$({ \frac 2 3 })^{-2}}$$

6. Sep 17, 2009

### Biaach

YES!! THAT IS EXACTLY WHAT I MEAN :)
Can any1 help me with this now? :)

7. Sep 17, 2009

### Integral

Staff Emeritus
Ok so you have:

$$\frac {2^{-2}} 3$$

What do you know about negitive exponents?

8. Sep 17, 2009

### Biaach

I do know that you have to multiply it with the numerator and you get a negetive answer.

so -2 x 2 = -4
and it would be
-4 over 3

9. Sep 17, 2009

### Integral

Staff Emeritus
No, that will not work. So do you understand the meaning of $2^{-1}$?

10. Sep 17, 2009

### Biaach

isnt $2^{-1}$ = -2?

Explain other details please

11. Sep 17, 2009

### Integral

Staff Emeritus
Nope!

$$2^{-1} = \frac 1 2$$

12. Sep 17, 2009

### Math Is Hard

Staff Emeritus
13. Sep 17, 2009

### Elucidus

Understanding the meaning of 2-1 is critical to handling any question of this type and your original question in particular.

What does your instructor/notes/text give as the definition of a-n?

How would you apply that definition to 2-1?

--Elucidus

14. Sep 17, 2009

### Biaach

How?

15. Sep 17, 2009

### Math Is Hard

Staff Emeritus
Look at the link I posted.

16. Sep 17, 2009

### Biaach

She told me to multiply the numerator with the exponent i think, and the answer would be a negative number

17. Sep 17, 2009

### Biaach

Oh and she said something about Reciprocal

18. Sep 17, 2009

### Elucidus

From the Product Rule of Exponents we want

$$2^1 \cdot 2^{-1} = 2^{1+(-1)} = 2^0 = 1$$.

But 21 = 2 so

$$2 \cdot 2^{-1} = 1$$ implies

$$2^{-1} = \frac{1}{2}$$

by dividing both sides by 2.

--Elucidus

19. Sep 17, 2009

### Integral

Staff Emeritus
Don't you have a textbook?

20. Sep 17, 2009

### Biaach

Can you give an example using the problem i posted?