Earth's acceleration due to gravity

[coolzero]

Homework Statement

What is the acceleration due to gravity at a distance of 2 Earth radii above Earth's surface?

Homework Equations

I'm lost with this question, can someone help. THanks

The Attempt at a Solution

 

[SteamKing]

Ever heard of this Newton fellow? He had some kind of formula for this a while back.

 

[HomogenousCow]

This has to be one of the most straightforward questions ever asked around here.