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# stumped on a seemingly simple math problem..

Discussion in 'Options' started by cdcaveman, Feb 5, 2013.

1. ### cdcaveman

i figure this relates so much to options .. some of you must know this..

find the dervative.. of

3/(2x)

i thought you bring factor so you don't have fractions, put everything to a power.. like sqrt(x) is x^1/2 i'm very good at much more complex questions relative to this..
a simple one is differentiate f(x) = x(x^2+3)
=x^3+3x
f'(x) =3x^2+3
thats simple..

so question is.. how to find the derivative of 3/(2x) i'm using parenthesis here so you don't think its three halfs of x .. its three over two times x..

2. ### hft_boy

It's like (3/2) * x^-1. Use the power rule and you get -1 * (3/2) * x^-2.

dx/dy for a quotient = ((derivitive of the numerator)(denominator)-(numerator)(derivitive of the denominator))/ (denominator)^2

4. ### cdcaveman

because 3/(2x) = 3/2 *1/x

there for lifting the x from the denominator you get

3/2(x^-1)

then you differentiate

-1 * (3/2) ... as the first part..
then subtract 1 from the exponent of x.. putting it at X^-2
so you end up with

-3/2x^-2

that sure seems right.. and follows what you are saying..

5. ### Eyez

-(3x^-2)/2 or -3/(2x^2)

6. ### cdcaveman

parenthesis to be explicit..

i got negative three halfs X to the negative second..

-3/2(x)^-2

8. ### cdcaveman

now.. (3/2)*((x^-2)/1) is the same as (3/2)*(1/(x^2))

yes moving the exponent up makes it negative and the reverse respectively..
such that negative three over 2x^2 is the same thing as 3/2( x ^-2)

9. ### Eyez

I guess im being a syntax nazi lol...

10. ### cdcaveman

at least we aren't actually arguing about the answer being right haha

#10     Feb 5, 2013
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