F(a) is minimal, so g(a) is f(0)=? 0 and f(a)=? Answer? (3-a) The smaller of the two.

1 & lt； When a≤3, a? >0,? 3? -? a≥0，？ f(a)？ =? Answer? (3-a)≥0，？ G(a) at this time? =? 0

Answer? & gt？ 3 o'clock, a? >0,? 3? -? Answer? & lt0,? f(a)？ =? Answer? (3-a)？ & lt0,? G(a) at this time? =a？ (3-a)

(2)

Answer? & lt？ When-1, just compare f(0) with the minimum value f( 1).

f(0)= 0； ? Answer? & lt- 1,? 3a？ & lt？ -3,? f( 1)=？ 3a？ -? 1? & lt？ -4? & lt？ 0

g(a)？ = f( 1) = 3a？ -? 1

It is easy to understand with reference to the picture below.