Calculus1
23 Online
OpenStudy (anonymous):
f(x)=2x^4x
Logarithmic Derivatives
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OpenStudy (anonymous):
@jim_thompson5910
jimthompson5910 (jim_thompson5910):
4 is the exponent? or 4x is?
OpenStudy (anonymous):
4x,
2^(4x)
jimthompson5910 (jim_thompson5910):
ok thx
OpenStudy (anonymous):
it says f(3)'
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jimthompson5910 (jim_thompson5910):
y = 2x^(4x)
ln(y) = ln( 2x^(4x) )
ln(y) = 4x*ln( 2x )
derive both sides with respect to x, then solve for y'
OpenStudy (anonymous):
1/y?
jimthompson5910 (jim_thompson5910):
the derivative of ln(y) with respect to x is ( y' )/y
OpenStudy (anonymous):
I see. is this for left hand?
jimthompson5910 (jim_thompson5910):
yes
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OpenStudy (anonymous):
ok,
OpenStudy (anonymous):
what do i do for right hand?
jimthompson5910 (jim_thompson5910):
use the product rule
OpenStudy (anonymous):
4x(1/2x)+(in2x)(4)?
jimthompson5910 (jim_thompson5910):
ln is lower case L, then n
not i then n
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jimthompson5910 (jim_thompson5910):
oh wait, made a typo, hold on while I fix it
jimthompson5910 (jim_thompson5910):
y = 2x^(4x)
ln(y) = ln( 2x^(4x) )
ln(y) = ln( 2) + ln( x^(4x) )
ln(y) = ln( x^(4x) ) + ln( 2)
ln(y) = 4x*ln( x ) + ln( 2)
( y' )/y = 4*ln( x )+(4x/2x)*2
( y' )/y = 4*ln( x )+4
y' = y ( 4*ln( x )+4 )
y' = 2x^(4x) * ( 4*ln( x )+4 )
I'll let you finish
OpenStudy (anonymous):
sure,
OpenStudy (anonymous):
mm product rule?
jimthompson5910 (jim_thompson5910):
so
f ' (x) = 2x^(4x) * ( 4*ln( x )+4 )
and you plug in x = 3 to find f ' (3)
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jimthompson5910 (jim_thompson5910):
yes
OpenStudy (anonymous):
It says incorrect again
jimthompson5910 (jim_thompson5910):
what did you get
OpenStudy (anonymous):
i got 20777773655.1287321453297664
jimthompson5910 (jim_thompson5910):
way too big lol
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OpenStudy (anonymous):
hahaha
jimthompson5910 (jim_thompson5910):
although, the answer is quite large...
jimthompson5910 (jim_thompson5910):
y = 2x^(4x)
ln(y) = ln( 2x^(4x) )
ln(y) = ln( 2) + ln( x^(4x) )
ln(y) = ln( x^(4x) ) + ln( 2)
ln(y) = 4x*ln( x ) + ln( 2)
( y' )/y = 4*ln( x )+(4x/2x)*2
( y' )/y = 4*ln( x )+4
y' = y ( 4*ln( x )+4 )
y' = 2x^(4x) * ( 4*ln( x )+4 )
f ' (x) = 2x^(4x) * ( 4*ln( x )+4 )
f ' (3) = 2(3)^(4(3)) * ( 4*ln( 3 )+4 )
f ' (3) = 8,922,308.90641656
jimthompson5910 (jim_thompson5910):
of course, you'll leave off the commas
they're just there for display purposes
OpenStudy (anonymous):
2.0777?
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jimthompson5910 (jim_thompson5910):
how did you get that?
OpenStudy (anonymous):
by my cauclator,
OpenStudy (anonymous):
it says 2.077777366e10
jimthompson5910 (jim_thompson5910):
oh, that's close I guess, but what I got should be the correct answer
OpenStudy (anonymous):
what is ur answer?
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jimthompson5910 (jim_thompson5910):
i posted it above
jimthompson5910 (jim_thompson5910):
see it?
OpenStudy (anonymous):
yes, omg,
you are math talent
jimthompson5910 (jim_thompson5910):
no, that would be the calculator lol
jimthompson5910 (jim_thompson5910):
i wish i could calculate that in my head
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OpenStudy (anonymous):
thank you, the way you write is clear to see,
easy to learn
jimthompson5910 (jim_thompson5910):
yw
OpenStudy (anonymous):
can i post more questions?
jimthompson5910 (jim_thompson5910):
sure