1. ## Tough Problem

1)The electric field at apoint P(x,y,z) due to a point charge q located at the origin is given by the inverse square field
E=qr/||r||^3
where r=xi+yj+zk
(a)Suppose S is a closed surface,Sa is a sphere x^2+y^2+z^2=a^2 lying completely within s, and D is the region bounded between S and Sa.Show that the outward flux of E for the region D is zero.
(b)Use the result of part (a) to prove Gauss's Law:
int int (E.n)dS=4*pi*q
that is, the outward flux of the electric field E through any closed surface (for which the divergence theorem applies) contaning the origin is 4*pi*q.

2)int int y^2/x dA,where R isthe region bounded by the graphs y=x^2,y=x^2/2,x=y^2,x=y^2/2;u=x^2/y,v=y^2/x.

In the question above,"int int" means double integral.Any idea about the question.Too tough for me.

2. nobody know how to solve it?