We have, dxdy+4x3y=7 ( where y=f(x))
This is a linear differential equation.
Integrating factor, I.F.=e∫4x3dx=e43lnx=x43
So, integrating the given differential equation using I.F.
⇒y.x43=∫7.x43dx
⇒y.x43=7.74x47+C
⇒y(x43)=4x47+C
⇒f(x)=4x+Cx4−3
⇒x→0+limxf(x1)⇒x→0+limx(x4+Cx43)=4