1. Diketahui f(x) = 2x-1, g(x) = 5-3x. Tentukanlah f o g (x)!
f o g (x) = f (5-3x)
= 2 (5-3x) – 1
= 10 – 6x – 1
= 9 – 6x
= -6x + 9
2. Diketahui f(x) dan g(x) seperti nomor 1 dan h(x) = 2x.x, tentukanlah f o g o h (x)!
f o g o h (x) = f o g (2x.x)
= f {5-3(2x.x)}
= f {5-6x.x)
= 2 (5-6x.x)-1
= 10 – 12x.x – 1
= 9 – 12x.x
= -12x.x + 9
3. Dari soal nomor 2, tentukanlah f o g o h (-2)!
f o g o h (-2) = f o g (2x.x)
= f {5 – 3(2x.x)}
= f (5 – 6x.x)
= 2 (5 – 6x.x) – 1
= 10 – 12x.x – 1
= 9 – 12x.x
= 9 – 12(-2)(-2)
= 9 – 12(4)
= 9 – 48
= - 39
4. Diketahui f(x) = 3x-2, g(x) = 6-6x dan h(x) = x.x. tentukanlah h o f o g (x)!
h o f o g (x) = h o f (6 – 6x)
= h {3 (6 – 6x) – 2}
= h ( 18 – 18x – 2)
= h ( 16 – 18x)
= (16 – 18x)(16 – 18x)
= 256 – 288x – 288x + 324x.x
= 256 – 576x + 324x.x
= 324x.x – 576x + 256
5. Dari soal nomor 4, tentukanlah g o f o h (1)!
g o f o h (1) = g o f (x.x)
= g {3 (x.x) – 2}
= g (3x.x – 2)
= 6 – 6(3x.x – 2)
= 6 – 18x.x + 12
= 18 – 18x.x
= 18 – 18(1)(1)
= 18 – 18
= 0
