The disturbance y(x, t) of a wave propagating in the positive x...

The disturbance $y(x, t)$ of a wave propagating in the positive $x$-direction is given by $y=\frac{1}{1+x^2}$ at time $t=0$ and by $y=\frac{1}{\left[1+\left(x-1^2\right)\right]}$ at $t=2 \mathrm{~s}$, where $x$ and $y$ are in meters. The shape of the wave disturbance does not change during the propagation. The velocity of wave in $\mathrm{m} / \mathrm{s}$ is