The number of characteristic curves of the PDE $(x^2+2y)u_{xx}+(y^3-y+x)u_{yy}+x^2(y-1)u_{xy}+3u_x+u=0$ passing through the point $x =1$, $y =1$ is
1. $0$
2. $1$
3. $2$
4. $3$
how can i solve this problem.please help anybody
The number of characteristic curves of the PDE $(x^2+2y)u_{xx}+(y^3-y+x)u_{yy}+x^2(y-1)u_{xy}+3u_x+u=0$ passing through the point $x =1$, $y =1$ is
1. $0$
2. $1$
3. $2$
4. $3$
how can i solve this problem.please help anybody