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Daerah asal fungsi (f – g)(x) adalah

D = D ∩D
f – g f g
= {x | x∈ } ∩ {x | x∈ }
= {x | x∈ }

c) (f × g)(x) = f(x) × g(x)
= (x + 3) × (x – 9)
2
= x + 3x – 9x – 27
2
3
Daerah asal fungsi (f × g)(x) adalah

D = D ∩D
f × g f g
= {x | x∈ } ∩ {x | x∈ }

= {x | x∈ }
  f   f ( ) x
=
d)    ( ) = ) =
x ( 
x
 g    g ( )
x +3
=
x 2 − 9
x +3
=
(x × +3) −(x 3)
1
=
x −3

D = D ∩D dan g(x) ≠ 0
f f g
g
= {x | x∈ } ∩ {x | x∈ } dan x – 9 ≠ 0}
2
= {x | x∈ } dan (x + 3) (x – 3) ≠ 0}

= {x | x∈ } dan x ≠ –3, x ≠ 3}

= {x | x∈ , x ≠ –3, x ≠ 3}

81
Matematika