$[50$ points$]$ The velocity vector $V=(u,v)$ of a two$-$dimensional irrotational flow is given by

$u=2x+1,v=-2y$

where the velocity has the units of $\frac{m}{s}$ with $x$ and $y$ in meter.

$($a$)$ Find the acceleration vector a and determine the value of $a$ at the origin $0,y=0).$

$($b$)$ Show that the continuity equation is satisfied.

$($c$)$ Given $=0$ at the point