[tex](1)\\direct\ variation\ between\ x\ and\ y:\ \ \ y=k\cdot x\ \ \ and\ \ \ k\in\ R\\\\Ans.\ NOT\ direct\ is\ D\\\\(2)\\f(x) = m\cdot x\ \ \ and\ \ \ f(6)=8\\\\ \Rightarrow\ \ \ m\cdot 6=8\ \ \ \Rightarrow\ \ \ m= \frac{8}{6} = \frac{4}{3} \ \ \ \ \Rightarrow\ \ \ \ Ans.\ D\\\\(3)\\f(x)=30x\ \ \ \Leftrightarrow\ \ \ \frac{f(x)}{x} =30\ \ \ \ \ \ \Rightarrow\ \ \ \ constans=30\ \ \ \ Ans.\ B.[/tex]
[tex]\\\\(4)\\f(x)=m\cdot x\ \ and\ \ f(8)=56\\\\m\cdot8=56\ \ \Leftrightarrow\ \ m= \frac{56}{8} =7\ \ \Rightarrow\ \ \ f(x)=7x\ \ \ \Rightarrow\ \ \ f(2)=7\cdot2=14\\\\Ans.\ D.[/tex]
