Question

Please help me find a common denominator for 1/sqrt(9+h) and 1/sqrt9

Answer 1

It should be sqrt(81 + 9h)

Answer 2

Multiply sqrt(9+h) and sqrt (9)

Answer 3

That isnt right..

Answer 4

let me get someone to help ya quick

Answer 5

thanks for coming hero

Answer 6

I just hate when it takes so damn long for the page to load.

Answer 7

I may have asked the wrong question. I have to subtract those two fRACTIONS from one another I may be asking for help with the wrong thing.

The equation is 1/sqrt(9+h)-1/sqrt9 all over h and I am solving for h. How do I get rid of the square roots so I can find what h is?

Answer 8

Well, sqrt{9} = 3 for starters

Answer 9

sqrt9-h over 9-9+h?

Answer 10

@mertsj you should respectfully allow me to continue helping since I have already begun. I know you're probably going to post a full solution, but I was in the middle of helping the person with it step by step. You should do what people like Fool for Math do and just continue to allow me to help the person. There are plenty other questions you could be helping others with.

Answer 11

Well, except that the asked asked me for help.

Answer 12

Why did you delete your post then?

Answer 13

You could have just said that rather than delete it

Answer 14

how is the denominator sqrt (9-h)*(9+h)?

Answer 15

It's called conjugation

Answer 16

I would like to help you but I must wait until Hero is done.

Answer 17

Go ahead Mertsj. You help people by posting the full solutions rather than guiding them throught the problem. If that's how you want to help, then by all means go ahead.

Answer 18

can someone help me figure out what to do after i have that fraction?

Answer 19

I also would like to help, but I have to deal with @mertsj interrupting my explanations.

Answer 20

he is gone now.

Answer 21

please help me?

Answer 22

Actually, just multiply the first fraction by \[\frac{\sqrt{9+h}}{\sqrt{9+h}}\]

Answer 23

okay I have sqrt(9+h)over 9+h - 1/3 all over h?

Answer 24

There's no minus. We're adding the fractions. Sorry if I confused you earlier

Answer 25

Now I may have no choice but to post the full solution.

Answer 26

\[\frac{1}{\sqrt{9+h}}+\frac{1}{\sqrt{9}}=\frac{1}{\sqrt{9+h}}+\frac{1}{3}\]=

Answer 27

original equation is minus 1/sqrt 9

Answer 28

For some reason everyone else thought it was plus

Answer 29

\[\frac{3}{3\sqrt{9+h}}-\frac{\sqrt{9+h}}{3\sqrt{9+h}}=\frac{3-\sqrt{9+h}}{3\sqrt{9+h}}\]

Answer 30

now I am just confused :(

Answer 31

There's still a square root in the denominator, but okay @mertsj

Answer 32

I do believe that the problem asked to find the common denominator for the two fractions. as I have shown, the common denominator is 3sqrt(9+h)

So if you disagree or are confused, please clarify exactly what the problem is. To rationalize the denominator or to find the common denominator.
In any case I have other things to do that fuss about such stupidity.

Answer 33

Well, I see your point, @mertsj, however, if you rationalize, you end up with a common denominator of 3(9+h) or 27 + 3h

Answer 34

\[f \prime(a)= \lim_{h \rightarrow 0} (1/\sqrt{9+h})-1/\sqrt{9})/h\] is where I need to end up I need the steps to easily sub in 0 for h so that I do not have a 0 in the denominator.

Answer 35

You should have just posted that to begin with

Answer 36

i did in a previous problem and no one helped me so I thought I would try to get help with the steps I knew came next in smaller easier problems. But IF you could help me with this as is it would be greatly appreciated :)

Answer 37

Then afterwards, you could have simply stated, "I'm having trouble finding a common denominator".

Answer 38

I will try to help

Answer 39

i just basically need to get the h out of the denominator

Answer 40

Yes, it's actually simpler than you think. I will write it out

Answer 41

okay thank you

Answer 42

Well, it wasn't as simple as I originally thought but it is doable. It essentially comes down to remembering distribution and simplification rules

Answer 43

I see why you're having difficulty with this. Again I want to stress posting the complete problem the first time. It would have saved everyone a lot of time.

Answer 44

Just to confirm:

\[f'(a) = \lim_{h \rightarrow 0} \frac{\frac{1}{\sqrt{9+h}} - \frac{1}{\sqrt{9}}}{h}\]

Is that correct?

Answer 45

you guys are still at it?

Answer 46

yes
that is correct

Answer 47

congrats on the thoroughness hero!

Answer 48

Only because at the last minute she posts the actual problem she's working with.

Answer 49

oh, lol

Answer 50

im sorry.. jeez.

Answer 51

Not to worry. I will get you the solution

Answer 52

http://www3.wolframalpha.com/Calculate/MSP/MSP1651a150ebi73g3hiad0000397e168b6gc40hb5?MSPStoreType=image/gif&s=32&w=440&h=554

Answer 53

You will find the solution there. Sorry for the trouble.

Answer 54

the all-mighty wolfram!

Answer 55

I wonder if you had to find the solution the old fashioned way

Answer 56

Because you wrote f'(a)

Answer 57

A proper solution will be posted before I go to bed.

Answer 58

wait so what you posted isnt right?

Answer 59

f'(a) = -1/54 is correct

It's just that the solution steps that wolfram alpha posted aren't the proper steps for posting f'(a) using the definition of a derivative which is what you are working on.

Answer 60

oh.. well how do I do that?

Answer 61

Well, I checked with a personal source I have (calculus expert) and even they admit that it is difficult to find an approach that would cancel the fraction 1/h

Answer 62

:'(

Answer 63

okay so i really need help i have class at 6 which is in one hour @Mertsj can u help?

Answer 64

I finally have the solution and I will be posting it shortly.

Answer 65

okay thank you very much!!

Answer 66

thank you sooo much you saved my butt!!

Answer 67

where did u go to get that help @Hero

Answer 68

Wow that was brillant!

Answer 69

What makes you think I went to anybody? The only thing that I did differently was instead of trying to conjugate the denominator, I decided to conjugate the numerator. I would have done the steps on here, but it lags too much and plus using that drawing board is just awful.

Answer 70

On top of that, you should have just posted the original problem from the beginning and it would have been solved in 10 minutes at most.

Answer 71

it was just a question sorry

Answer 72

how did you get the -h in the 4th step from the bottom?

Answer 73

nvmfigured it out