i have a quick question, which hopefully someone can straighten out for me.(adsbygoogle = window.adsbygoogle || []).push({});

i was reading this http://en.wikipedia.org/wiki/Rayleigh-Jeans_law

at the part titled 'Consistency of frequency and wavelength dependent expressions'

i follow the logic, but am confused about where the - sign goes after the differentiation.

they differentiate, and get the negative, but when this is multiplied by the frequency dependent form, it disappears.

and i now know this cannot be a typo, because i have found other references which also have the answer as a positive.

could someone please explain where this negative goes, and for what reason.

thanks :)

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# Rayleigh-Jeans approxomation

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