Let for f(x)=7 tan^8 x + 7 tan^6 x - 3 tan^4 | vedclass

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(C) Given $f(x) = (7 	an^6 x - 3 	an^2 x)(	an^2 x + 1) = (7 	an^6 x - 3 	an^2 x)(\sec^2 x)$.$I_1 = \int_0^{\pi/4} (7 	an^6 x - 3 	an^2 x)(\sec^

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(C) Given $f(x) = (7 	an^6 x - 3 	an^2 x)(	an^2 x + 1) = (7 	an^6 x - 3 	an^2 x)(\sec^2 x)$.$I_1 = \int_0^{\pi/4} (7 	an^6 x - 3 	an^2 x)(\sec^2 x) \, dx$.Let $	an x = t$,then $\sec^2 x \, dx = dt$. As $x 	o 0, t 	o 0$ and as $x 	o \pi/4, t 	o 1$.$I_1 = \int_0^1 (7t^6 - 3t^2) \, dt = [t^7 - t^3]_0^1 = 1 - 1 = 0$.Now,$I_2 = \int_0^{\pi/4} x f(x) \, dx = \int_0^{\pi/4} x \frac{d}{dx} (	an^7 x - 	an^3 x) \, dx$.Using integration by parts: $I_2 = [x(	an^7 x - 	an^3 x)]_0^{\pi/4} - \int_0^{\pi/4} (	an^7 x - 	an^3 x) \, dx$.Since $	an(\pi/4) = 1$,the boundary term is $0 - 0 = 0$.$I_2 = - \int_0^{\pi/4} 	an^3 x (	an^4 x - 1) \, dx = - \int_0^{\pi/4} 	an^3 x (	an^2 x - 1)(	an^2 x + 1) \, dx$.Let $	an x = t$,then $\sec^2 x \, dx = dt$.$I_2 = - \int_0^1 t^3(t^2 - 1) \, dt = - \int_0^1 (t^5 - t^3) \, dt = - [\frac{t^6}{6} - \frac{t^4}{4}]_0^1 = - (\frac{1}{6} - \frac{1}{4}) = - (\frac{2-3}{12}) = \frac{1}{12}$.Thus,$7 I_1 + 12 I_2 = 7(0) + 12(\frac{1}{12}) = 1$.

Let for $f(x)=7 \tan^8 x + 7 \tan^6 x - 3 \tan^4 x - 3 \tan^2 x$,$I_1 = \int_0^{\pi/4} f(x) \, dx$ and $I_2 = \int_0^{\pi/4} x f(x) \, dx$. Then $7 I_1 + 12 I_2$ is equal to:

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