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Let <font size = '4'><math>\chi (w) = \pi \delta (w - 6) - \pi \delta (w - 3)</math></font>
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Let <font size = '4'><math>\chi (w) = \frac{\pi}{j} 4\delta (w - 6) - \frac{\pi}{j} 4\delta (w + 6)</math></font>
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Then <math>x(t) = \frac{1}{2\pi}\int^{\infty}_{-\infty} \chi (w) e^{jwt}dw</math>
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<math>x(t) = \frac{1}{2\pi} [\frac{4\pi}{j}\int^{\infty}_{-\infty} \delta(w-6)e^{jwt} dw - \frac{4\pi}{j} \int_{-\infty}^{\infty} \delta(w+6)e^{jwt} dw]</math>
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<math>x(t) = \frac{2}{j}e^{j6t} - \frac{2}{j}e^{-j6t} = 4[\frac{e^{j6t} - e^{-j6t}}{2j}] = 4sin(6t)</math>

Revision as of 13:54, 8 October 2008

Let $ \chi (w) = \frac{\pi}{j} 4\delta (w - 6) - \frac{\pi}{j} 4\delta (w + 6) $

Then $ x(t) = \frac{1}{2\pi}\int^{\infty}_{-\infty} \chi (w) e^{jwt}dw $

$ x(t) = \frac{1}{2\pi} [\frac{4\pi}{j}\int^{\infty}_{-\infty} \delta(w-6)e^{jwt} dw - \frac{4\pi}{j} \int_{-\infty}^{\infty} \delta(w+6)e^{jwt} dw] $

$ x(t) = \frac{2}{j}e^{j6t} - \frac{2}{j}e^{-j6t} = 4[\frac{e^{j6t} - e^{-j6t}}{2j}] = 4sin(6t) $

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