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  • Subject: calculus help (mr. math are you out there?)
Subject: calculus help (mr. math are you out there?)
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Posted by: xXGODLYSKILLSXx
couldnt agree more achronos
<--------- Bungie fanboy

hey guys so I'm doing the instantaneous rate of change using the difference quotient and I have a test on monday and I'm studying but I don't know how to do some of them can someone help me? ok for these problems I have this equation: http://www.mathwords.com/d/difference_quotient.htm
except i'm finding the instantaneous rate of change. I have for f(x)=2/x and for the a/x-zero = 2. I just have to get the H from the bottom out and multiply it by zero to find the limit.

  • 12.15.2012 7:49 AM PDT

BTW Elites rule!

And I am probably just trolling you right now....especially if it is a controversial thread

Wait a moment, how far are you into this calculus class? Isn't this pre-calculus?

  • 12.15.2012 7:55 AM PDT

Expressing my strong liberal views without shame. Favorite quotes below:

"Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe."
"One starts to live when he can live outside himself."

- Albert Einstein

What are you asking?

  • 12.15.2012 7:57 AM PDT
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Posted by: xXGODLYSKILLSXx
couldnt agree more achronos
<--------- Bungie fanboy


Posted by: Buckysaurus
Wait a moment, how far are you into this calculus class? Isn't this pre-calculus?

Idk i'm in tenth grade and it's just called math

oh im in a different country btw not the us anmore

  • 12.15.2012 8:03 AM PDT


Posted by: ll 0wN4g3 ll
hey guys so I'm doing the instantaneous rate of change using the difference quotient and I have a test on monday and I'm studying but I don't know how to do some of them can someone help me? ok for these problems I have this equation: http://www.mathwords.com/d/difference_quotient.htm
except i'm finding the instantaneous rate of change. I have for f(x)=2/x and for the a/x-zero = 2. I just have to get the H from the bottom out and multiply it by zero to find the limit.

(2/(x+h)-2/x)/h

multiply by x(x+h)/x(x+h) which is just 1, so it is allowed. Basically this step just allows you to add the terms in the numerator by giving them the same denominator. I will expand on this now as it might be confusing. Focus on just the numerator without the h in the denominator to make it easier to read.

2/(x+h)-2/x

To add the terms, they have to have the same denominator. So the first term needs to be multiplied by x/x yielding 2x/x(x+h)

the second term needs to be multiplied by (x+h)/(x+h), yielding -2(x+h)/x(x+h). So at this point you have

2x/x(x+h)-2(x+h)/x(x+h)

Now, you can add the terms with common denominator, so

[2x-2(x+h)]/x(x+h)

Now, dividing by the h that was originally in the denominator.

get

[2x-2(x+h)]/(xh(x+h))

add terms in the numerator

-2h/(xh(x+h)

divide out the h

-2/(x(x+h))

or

-2/(x^2+hx)

take limit as h->0

-2/x^2

[Edited on 12.15.2012 8:16 AM PST]

  • 12.15.2012 8:03 AM PDT

BTW Elites rule!

And I am probably just trolling you right now....especially if it is a controversial thread

Also, screw the quotient rule use the shortcuts if you know them....because it gets rather lengthy like that^^^^

2x^-1
so
-2x^-2
so
-2/x^2

  • 12.15.2012 8:38 AM PDT


Posted by: Buckysaurus
Also, screw the quotient rule use the shortcuts if you know them....because it gets rather lengthy like that^^^^

2x^-1
so
-2x^-2
so
-2/x^2

That isn't the question, so if asked on an exam he would get zero credit for using the shortcut. Plus, they most likely don't know the differentiation rules yet. It really isn't lengthy though, I just went into a lot of detail explaining every step.


[Edited on 12.15.2012 8:42 AM PST]

  • 12.15.2012 8:41 AM PDT

BTW Elites rule!

And I am probably just trolling you right now....especially if it is a controversial thread


Posted by: SRQ baller24

Posted by: Buckysaurus
Also, screw the quotient rule use the shortcuts if you know them....because it gets rather lengthy like that^^^^

2x^-1
so
-2x^-2
so
-2/x^2

That isn't the question, so if asked on an exam he would get zero credit for using the shortcut. Plus, they most likely don't know the differentiation rules yet.



Yeah, definitely. The differentiation rules are so much nicer though.

  • 12.15.2012 8:44 AM PDT
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Posted by: xXGODLYSKILLSXx
couldnt agree more achronos
<--------- Bungie fanboy

The teacher had -1/2+h and when h is 0 it's -1/2.. !!

  • 12.16.2012 9:44 AM PDT