functions question

Question

Let f(x)=3x-1 and g(x)=x^2+4

 

find (f g)(-2)

Answer 1

f(x ) = 3X -1     g( x ) = X^2 +4

 

  ( f +g) ( -2 )= [( 3(-2)  -1 +(-2^2)  + 4] =

                     = ( -6 - 1 +4 +4 ) = 1

 

  ( f - g ) ( -2) = [ 3(-2) -1 - ( -2^2 +4 ) ]=

                     = ( -7 -8) = -15

 

  (f ° g ) (-2 ) = [ 3 (-2^2 + 4) - 1 ] =

 

                    =  3( 8) - 1 = 23