Mathematics
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OpenStudy (anonymous):
Hi all! How do I take the derivative of this function? (attached)
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OpenStudy (anonymous):
OpenStudy (anonymous):
It's making my head hurt XD
hartnn (hartnn):
use the log rules,
log A/B = .... ?
hartnn (hartnn):
and
\(\log \sqrt a = \log a^{1/2}= (1/2)\log a\)
OpenStudy (anonymous):
ok I'll try and work through it
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OpenStudy (anonymous):
is the first step ln(a^2 - z^2)^1/2 - ln(a^2 + z^2)^1/2 ?
hartnn (hartnn):
yeah, it can be
OpenStudy (anonymous):
lol ok
hartnn (hartnn):
now use this
\(\log \sqrt a = \log a^{1/2}= (1/2)\log a\)
OpenStudy (anonymous):
(1/2)ln(a^2 -z^2)-(1/2)ln(a^2 +z^2)
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hartnn (hartnn):
yes, now differentiation will be easier
OpenStudy (anonymous):
derivative of lnx is 1/x
OpenStudy (anonymous):
should I do that?
hartnn (hartnn):
yes, and you;ll need chain rule too
OpenStudy (anonymous):
f'(g)*g'
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hartnn (hartnn):
yes
OpenStudy (anonymous):
ok
OpenStudy (anonymous):
(1/2)(1/(a^2 -z^2))(2a-2z)-(1/2)(1/(a^2 +z^2))(2a+2z)
OpenStudy (anonymous):
is this right?
hartnn (hartnn):
'a' is constant, its derivative = 0
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OpenStudy (anonymous):
aha but z is still some function, right?
hartnn (hartnn):
yes
OpenStudy (anonymous):
so, (1/2)(1/(a^2 -z^2))(-2z)-(1/2)(1/(a^2 +z^2))(2z) ?
hartnn (hartnn):
yep!
OpenStudy (anonymous):
ok so, is the first part -4z/(a^2 -z^2)
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hartnn (hartnn):
yes
OpenStudy (anonymous):
overall -4z/(a^2 -z^2) -4z/(a^2 +z^2)
OpenStudy (anonymous):
?
hartnn (hartnn):
seems correct to me
OpenStudy (anonymous):
should/can I simplify further?
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hartnn (hartnn):
yes,
-4z can be factored, then take LCM , some terms are getting cancelled...
OpenStudy (anonymous):
least common multiple=lcm?
hartnn (hartnn):
yes
OpenStudy (anonymous):
hmm, I think if I factor it out, that should be enough
OpenStudy (anonymous):
too much time spent studying math XD
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hartnn (hartnn):
but it can be further simplified...
OpenStudy (anonymous):
hmm ok
OpenStudy (anonymous):
so I assume I take (a^2 -z^2)/(a^2 -z^2)
OpenStudy (anonymous):
?
OpenStudy (anonymous):
Well, I have to afk for a bit, then work on this some more. Thanks again as always! :)