Total Electric flux on two charges

[squintyeyes]

A point charge q1 = 9.00 nC is located at the origin, and a second point charge q2 = -3.00 nC is on the x-axis at x = 1.00 m. What is the total electric flux due to these two point charges through a spherical Gaussian surface centered at the origin and with radius

(a) 0.500 m?
E = ___________N m2/C
(b) 1.50 m?
E = ___________ N m2/C


so for part a i figure out that the net electric field is 432N/C in the positive i hat direction but what is the da and what are the limits to my integral?

 

[rl.bhat]

According to Gauss theorem, total flux across a spherical surface is
Φ = Q/εο, where Q is the net charge enclosed in the given spherical surface.