Solve all

Solve the following first-order partial differential equations a) pq u with u(0, y)= y, (b) p+q=pq %3D with u(x,0) =ax where a is a constant, O xp + yq = u with u(s,1)=-2s where s is a parameter, with ux,y)=-y at x 0. = bd (p) %3D (d) pq = xy with u(x,y) =-y at x=0. %3D