Find the explicit form general solution to the following first order ODEs. $($a$)$ du dx $+1$ x u $=$ e x $($b$)$ xeu du dx $+$ x $+$ e u $=03.$ Find the explicit form general solution to these too. $($a$)$ du dx $=$ u $2$ u $($b$)$ x $2$ du dx $+$ u $2$ xu $=0$