I'm unsure of how to approach this?

1) A point mass in is a distance d above a uniform infinite plane of mass, surface mass density o kg/m'. What is the force on the mass? Do this problem two ways: a) Explicitly compute the resultant of the of the gravitational force from all the mass elements on the sheet (an integral). b) Use Gauss' law to obtain the result. Do methods a) and b)agree? c) Now suppose the mass m is an extended spherically symmetric mass of radius ,here