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I have the two signals and need to determine whether they are energy type or power type: $$x_1(t)=A\cos(2\pi ft), -\infty<t<\infty$$ $$x_2(t)=1$$

I have solved the first one using the expression for the energy of the signal and found that energy is infinite so it must be a power signal. For the second one I don't know how to solve that as I don't know what limits to use.$$$$Any help will be appreciated.

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  • \$\begingroup\$ If no limits are given, I would assume plus/minus infinity as well. Or zero to infinity since it's about time....But it won't change the answer. \$\endgroup\$ – Eugene Sh. Feb 12 '18 at 19:14
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Write the energy integral for the second signal in the same way you did for the first.

You'll see that it is a power signal too, since its energy is infinite:

$$ E_2 = \int_{-\infty}^{+\infty}{|x_2(t)|^2}dt = \int_{-\infty}^{+\infty}dt = \lim_{T \,\to\, +\infty} \int_{-T/2}^{T/2}dt= +\infty $$

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  • \$\begingroup\$ It looks like the only problem OP has is that no time range is given as for the first one. \$\endgroup\$ – Eugene Sh. Feb 12 '18 at 19:12

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