Diketahui (f o g)(x) = x2 + 3x + 4 dan g(x) = 4x – 5. Nilai dari f(3) g(x) = 3 adalah

Kelas 10 Matematika
Bab Fungsi Komposisi

(fog) (x) = x² + 3x + 4
f (4x - 5) = x² + 3x + 4
f (4 . x/4 - 5) = (x/4)² + 3 . x/4 + 4
f(x - 5) = x²/16 + 3x/4 + 4
f(x + 5 - 5) = (x + 5)²/16 + 3(x + 5)/4 + 4
f(x) = (x + 5)²/16 + 3 (x + 5)/4 + 4

1] f(3) = (3 + 5)²/16 + 3 (3 + 5)/4 + 4
f(3) = 64/16 + 3 . 8/4 + 4
f(3) = 4 + 6 + 4
f(3) = 14

2] g(x) = 3
4x - 5 = 3
4x = 3 + 5
x = 8/4
x = 2