The annual net income of General Electric for the period 2009-2013 could be approximated by P(t) = -0.3912 + 5.2t - 4.1 billion dollars (4 s t s 8), where t is time in years since 2005.+ GE net income ($ billion) 20 15 10 O 5 6 A (a) Compute P'(t). P (t) = How fast was GE's annual net income changing in 2011? billion dollars per year