# Homework Help: Show equality

1. Aug 26, 2010

### wtfpurepwned

If f(x)= 5^x, show that

f(x+h) - f(x) / h = (5^x)(((5^h)-1) / h)

I need a step by step solution or some hints

2. Aug 26, 2010

### Dickfore

Do you know any properties of the exponential function?

3. Aug 26, 2010

### wtfpurepwned

like the law of exponents? i know most of them. ill apply the laws more thoroughly

Last edited: Aug 26, 2010
4. Aug 26, 2010

### Dickfore

Do you think the term "exponential function" has anything to do with the problem you have posed?

5. Aug 26, 2010

### wtfpurepwned

yes, when i see something like 5^x

6. Aug 26, 2010

### Dickfore

So, can you state some of the properties of the exponential function?

7. Aug 26, 2010

### wtfpurepwned

8. Aug 26, 2010

### Dickfore

Ok, so, if $f(x) = 5^{x}$, which one of those would you use (and in what direction, i.e. from left to right or right to left) to express $f(x + h)$?

9. Aug 26, 2010

### wtfpurepwned

not sure which one would work for that since i only understand the first 4-5 properties atm but if i have to do something id go with f(x+h) = 5^x + 5^h and that doesn't seem to make a whole lot of sense

10. Aug 26, 2010

### Dickfore

Hint:
$$f(x + h) = 5^{x + h}$$

not $5^{x} + 5^{h}$.

If you are not comfortable with this, I think you need to brush on your pre-calc syllabus.

11. Aug 26, 2010

### wtfpurepwned

okay i see how it works out now. didn't take calc after high school pre-calc and it's been 3 years, everything is in bit's and pieces..I'm currently brushing my *** off :( thanks for the help Dick