Question $6(6$ points$)$

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Consider the differential equation

$y^{\text{'}\text{'}}+9y=cos(t)$

Select all true statements.

Resonance is not possible in this case, since there is no friction.

When $=9,$ the solution will exhibit resonance.

Beats happens when the driving frequency equals the natural frequency, in the absenes of friction.

len the driving frequency equals the natural frequency, the absence of friction.

When $=3,$ the solution will exhibit resonance.

When $=9\mathrm{.}01,$ the solution will exhibit beats.