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**1. Homework Statement**

the volume charge density Pe= Po (1- (r^2/r0^2))

the sphere has a radius of r0

and r is measured from the center

for a point P inside the sphere (r<r0), determine the electric potential V if V=0 at infinity

**2. Homework Equations**

E= Qencl/ eps0*A= kQ/r^2

Qencl= int(Pe*4pir^2) dr

-int(E)= V

**3. The Attempt at a Solution**

first i found Qencl and evaluated it from 0 to r.

Qencl= 4pi*p0 (r^3/ 3 - r^5/5r0^2)

Then E= Po/eps0 ((r/3)- r^3/ 5r0^2)

then the -integral of E= V= p0/eps0 ( (r^2/ 6) - (r^4/20r0^2) - (7r02/60))

but this is the worng answer..any help?