Monday, August 13, 2012

What is the derivative of ln[(sqrt(x+4)*(x+3)^2)/(sqrt3(x+5)) + 50?

We  use  the following  formula , rules and
notations::


d/dxf(x) = f'(x) or
(f(x))'


d/dx (kx^n) =
k*nx^(n-1).


d/dx{ f(x)*g(x) } =  f'(x)g(x) -
f(x)g('x).


d/dx{ f(x)/g(x)} = [f'(x)*g(x)-
f(x)*g'(x)}/(g(x))^2.


d/dx f(g(x)) =  (df/dg )g'(x) , also
called chain rule


d/dx ln f(x) = {1/f(x)
}f'(x)


..............


Given
 f(x) =  ln[(sqrt(x+4)*(x+3)^2)/(sqrt3(x+5)) + 50?


RHS : 50
is treated as the 2nd term. And sqrt3(x+3) is treated as
(sqrt3)(x+5).


LHS : the one sided rectangular bracket [ is
ignored as there is no right pair inthe expression.


WE
consider:


f(x)  = u(x)/v(x)
+50,


where u(x) =
ln(sqrt(x+4)*(x+3)^2).


Therefore f'(x) = {u(x)/v(x)}'
+(50)'


f'(x) = {u'(x)v(x)-u(x)v,(x)}/{v(x)}^2
..............(1)
, as (50)' = 0.


u'(x) =
1/sqrt(x+4)*(x+3)^2 * {sqrt(x+4)*(x+3)^2}'


u'(x) =
{(1/2)(x+4)^(-1/2)*(x+3)^2 +
(x+4)^(1/2)*2(x+3)}/sqrt(x+4)*(x+3)^2


u'(x)={(x+3)^2
+4(x+4)(x+3)}/2(x+4)(x+3)^2


u'(x) = {x^2+6x+9+4x^2+28x+48}/
2(x+4)(x+3)62


u'(x) =
(5x^2+34x+57)/2(x+4)(x+3)^2


u'(x) =
(5x+19)(x+3)/2(x+4)(x+3) ^2


u'(x)
=(5x+19)/2(x+4)...........(2)


v(x) =
(sqrt3)(x+5)


v'(x) =
(sqrt3)(x+5)'


v'(x) =
sqrt3.


Substituting in (1) , the values
obtained in (2) and (3), we get:


f'(x) =
{{(5x+19)/2(x+4)}*(sqrt3)(x+5) + ln(sqrt(x+4)*(x+3)^2) *(sqrt3)(x+5)}/
((sqrt3)(x+5))^2


f'(x) = {sqrt3(5x+19)(x+5)
+2(sqrt3)(x+4)ln(sqrt(x+4)*(x+3)^2)}/3(x+5)^2.

No comments:

Post a Comment

How is Anne's goal of wanting "to go on living even after my death" fulfilled in Anne Frank: The Diary of a Young Girl?I didn't get how it was...

I think you are right! I don't believe that many of the Jews who were herded into the concentration camps actually understood the eno...