Google+ experienced an increase in the number of users between July 1, 2011 and February 1, 2012. The total number of users in millions can be modeled by the polynomial function G(x) = 0.000014437x³ -0.00406x² + 0.603x + 3.7, where x represents days after July 1, 2011. 

(a) Evaluate G(31) and interpret the result. 

(b) Graph y = G(x) in [0, 215, 20] by [0, 90, 10]. Does function G have any local extrema for the interval 0 ≤ x ≤ 215? 

(c) Where is function G increasing if its domain is 0 ≤ x ≤ 215?