A signal x(t) has the two-sided spectrum representation shown in Fig. 1.(a) Write an equat...

A signal x(t) has the two-sided spectrum representation shown in Fig. 1.

(a) Write an equation for x(t) as a sum of cosines.

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(b) Is x(t) a periodic signal? If so, determine its fundamental period and its fundamental frequency.

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(c) Explain why negative frequencies are needed in the spectrum.

Figure 1