- #1

This is a function and I suppose to calculate the value. But I am stuck. Thanks for your help.

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- Thread starter Learning
- Start date

- #1

This is a function and I suppose to calculate the value. But I am stuck. Thanks for your help.

- #2

enigma

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Originally posted by Learning

1/a+h+9 - 1/a+9 divide by h

Let me ask for clarification. You don't have any parenthesis, so the equation is a little ambiguous when looking at the screen.

Is this the equation:

or is it something different?

- #3

Thats exactly right, sorry I forgot the those. Its different on the computer than writing it. Thanks

- #4

enigma

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Ok,

Forum rules: you really should try the problem yourself first, so we can help where you got stuck. I can give you some pointers to get you started, though.

The trick is to get the h by itself on one side.

In this case, you'd first add (1/(a+9))/h to both sides, giving

Then, multiply both sides by h, giving

Give it a shot, and let us know how you do. Remeber, multiplying by X/X is the same as multiplying by 1.

- #5

- #6

enigma

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Give it a shot, post your work!

- #7

I'm lost. Please work with me here.

- #8

HallsofIvy

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I assume that you mean, not 1/(a+h+9) - (1/(a+9))/h = 0, as enigma said (because there was no equation, initially) but rather,

(1/(a+h+9)- 1/(a+9))/h simply because that's a fairly standard "derivative" problem.

The first thing you should do is add the fractions: since they have different denominators, you need to get the same denominator by multiplying the numerator and denominator of the first fraction by (a+9): (a+9)/((a+h+9)(a+9)) and the numerator and denominator of the second fraction by (a+ h+ 9): (a+ h+9)/((a+h+9)(a+9))

(I did not multiply out the denominator because there is no need to.)

Now we know

1/(a+h+9)- 1/(a+9)= (a+9)/((a+h+9)(a+9))-(a+ h+9)/((a+h+9)(a+9))

= (a+9-(a+h+9))/((a+h+9)(a+9))

= -h/((a+h+9)(a+9))

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