6. ( f o g )(x) = f [ g(x) ]
x² - 9x + 12 = 5 - g(x)
g(x) = -x² + 9x - 12 + 5
g(x) = -x² + 9x - 7
g(2) = -(2)² + 9.2 - 7
= -4 + 18 - 7 = 7
7. ( f o g )(x) = f [ g(x) ]
( x - 1 )² + 3 = f( x - 1 )
Misal : x - 1 = R
x = R + 1
[ ( R + 1 ) - 1 ]² + 3 = f(R)
(R)² + 3 = f(R)
R² + 3 = f(R)
f(x) = x² + 3
f(10) = -(10)² + 3
= -100 + 3 = -97
8. ( f o g )(x) = f [ g(x) ]
[tex] \frac{7x + 3}{5x - 9} = f(2x - 4) [/tex]
Misal : 2x - 4 = R
2x = R + 4
[tex]x = \frac{r + 4}{2} \\ \frac{7( \frac{r + 4}{2} ) + 3}{5( \frac{r + 4}{2}) - 9 } = f(r) \\ \frac{ \frac{7r + 28}{2 } + 3 }{ \frac{5r + 20}{2} - 9 } = f(r) \\ \frac{ \frac{7r + 28 + 6}{2} }{ \frac{5r + 20 - 18}{2} } = f(r) \\ \frac{ \frac{7r + 34}{2} }{ \frac{5r + 2}{2} } = f(r) \\ \frac{7r + 34}{2} \times \frac{2}{5r + 2} = f(r) \\ \frac{7r + 34}{5r + 2} = f(r) \\ \frac{7x + 34}{5x + 2} = f(x) \\ f(10) = \frac{7.10 + 34}{5.10 + 2} \\ = \frac{70 + 34}{50 + 2} \\ = \frac{104}{52} = 2[/tex]
