i got a better methord of solving such problems.

instead of considering multiple shells just consider one gaussian concentric sphere such that it touches the pt at which the ele fld has to be calc.

frm gauss eq

    _o  EdA = q 

  here q   =  _{[ 0]}^[x] dq  =    _[ 0]^[x] _o(r²-r³/a)dr

and,

EdA=EA= E 4x²

sub and solve u get E as the same. the steps r similar to the previous methord but the one is easier to understand.

EdA=EA is apllicable due to spherical symmetry(where A is the surface area of the gaussian sur). all u need to do is to calcutate the total charge enclosed and just plug it in the eq

 

this is applicable to any type of spherical charge dist evn a non conducting sphere.( this is 4 u akku).