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I'm reading this explanation of integrals with quadratics and the author pulled this out of nowhere. Is it obvious to everyone but me that this statement is true?

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    $(2a^2+2)^3=[2(a^2+1)]^3=2^3(a^2+1)^3$ This is true for any $a$, for $a=\tan x$ you get your equality.2013-08-05

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Since $2\tan^2 x + 2 = 2(\tan^2 x + 1),$ we see that $(2\tan^2 x + 2)^3 = 2^3(\tan^2 x + 1)^3.$

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    *facepalm. It's so obvious. Than$k$s.2012-10-19