In the wave equation, $22=12222$y$$x$2=1$v$22$y$$t$2,$ what can you say about v$?$

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If v is zero, the wave is a standing wave. $$

If v is positive, the wave is traveling in the $+$x direction, and if v is negative, the wave is traveling in the $-$x direction.

v must be positive. $$

v must be negative. $$

If v is positive, the wave is traveling in the $-$x direction, and if v is negative, the wave is traveling in the $+$x direction.$$