Answer:
Step-by-step explanation:
4). Given functions are,
[tex]f(x)=\frac{1}{3x}[/tex]
For [tex]x=\frac{1}{12}[/tex]
[tex]f(\frac{1}{12})=\frac{1}{3(\frac{1}{12})}[/tex]
[tex]=\frac{1}{\frac{1}{4}}[/tex]
[tex]=1\times\frac{4}{1}[/tex]
[tex]=4[/tex]
[tex]g(x)=\frac{1}{x^2}[/tex]
For [tex]x=\frac{1}{5}[/tex],
[tex]g(\frac{1}{5})=\frac{1}{(\frac{1}{5})^2}[/tex]
[tex]=\frac{1}{\frac{1}{25}}[/tex]
[tex]=25[/tex]
[tex]f(\frac{1}{12})-g(\frac{1}{5})=4-25[/tex]
[tex]=-21[/tex]
5). f(x) = -2x² + 3x - 8
f(k + 4) = -2(k + 4)² + 3(k + 4) - 8
= -2(k² + 8k + 16) + 3(k + 4) - 8
= -2k² - 16k - 32 + 3k + 12 - 8
= -2k² - 13k - 28
