Contoh Soal Fungsi Komposisi dan Fungsi Invers
1. Contoh soal Fungsi Komposisi 1. Misalkan f = {(1, 4), (2, 3), (3, 1), (4, 2)} dan g = {(1, 2), (2, 4), (3, 1), (4, 3)}, maka tentukanlah : a. f o g b. g o f Jawab : a. f o g = f [ g ] = f [ (1, 2), (2, 4), (3, 1), (4, 3) ] = {(1, 2) → (2, 3), (2, 4) → (4, 2), (3, 1) → (1, 4), (4, 3) → (3, 1)} = {(1, 3), (2, 2), (3, 4), (4, 1)} b. g o f = g [ f ] = g [(1, 4), (2, 3), (3, 1), (4, 2) ] = {(1, 4)→(4, 3), (2, 3)→(3, 1), (3, 1)→(1, 2), (4, 2)→(2, 4)} = {(1, 3), (2, 1), (3, 2), (4, 4)} 2. Diberikan dua buah fungsi yang masing-masing f (x) dan g (x) berturut-turut yaitu : f ( x ) = 5 x + 4 g ( x ) = 7 – x Tentukanlah: a. ( f o g ) ( x ) b. ( g o f ) ( x ) Jawab : a. ( f o g )( x ) = f ( g ( x )) = f ( 7 – x ) = 5 ( 7 – x ) + 4 = 35 – 5 x + 4 = 39 – 5 x b. (g o f)( x) = g ( f ( x )) = g ( 5 x + 4) = 7 – ( 5 x + 4) = 7 – 4 – 5 x = 3 – 5 x 3. Diketahui dua fungsi f(x)=x2−5x+4 dan \(g(x)= x^{2}+3x-6\). Tentukanlah nilai (f o g)(2) Jawab : (f o g)(2) = f [ g(2) ] =f [