What is the range of the relation? {(1, 2), (2, 4), (3, 2), (4, 6)}  A.{2, 4}  B.{1, 2, 3, 4, 6}  C.{2, 4, 6}  D.{1, 2, 3, 4}

Which relation is a function?  A.{(1, 2); (2, 3); (3, 4); (2, 5)}  B.{(1, 2); (1, 3); (1, 4); (1, 5)}  C.{(1, 2); (2, 3); (3, 4); (1, 5)}  D.{(1, 2); (2, 2); (3, 2); (4, 2)}

For the function f(x) = 2 – 3x, find f(4).  A.–5  B.12  C.–10  D.14
Which equation represents a direct linear variation?  A.y = x – 3  B.y=1/3x  C.y = x^2  D.y=1/x
Which is the direct linear variation equation for the relationship?

y varies directly with x and y = 12 when x = 4.
 
  A.y = 3^x  B.y = x + 8  C.y = 2x + 4   D.y = x – 8
Which is the quadratic variation equation for the relationship?

    y varies directly with x2 and y = 48 when x = 2.
 
  A.y = 4x^2  B.y = 4x  C.y = 12x^2  D.y = x^2 + 25

Write the inverse variation equation for the relationship: y varies inversely with x and y = 4 when x = 2.
  A.y = 2x  B.y=8/x  C.y = x + 2  D.y=1/2x



Answer :

[tex](1)\ \ \ \ range:\ \ \ \{2, 4, 6\}\ \ \ \Rightarrow\ \ \ Ans.\ C\\\\(2)\ \ \ function:\ \ \ \{(1, 2); (2, 2); (3, 2); (4, 2)\}\ \ \ \Rightarrow\ \ \ Ans.\ D\\\\(3)\ \ \ f(4)=2-3\cdot4=2-12=-10\ \ \ \Rightarrow\ \ \ Ans.\ C\\\\(4)\ \ \ direct:\ \ \ y=ax\ \ \ \Rightarrow\ \ \ y= \frac{1}{3} x\ \ \ \Rightarrow\ \ \ Ans.\ B\\\\(5)\ \ \ f(x)=ax\ \ \ and\ \ \ f(4)=12\\.\ \ \ \ \ \Rightarrow\ \ \ 12=a\cdot4\ \ \ \Rightarrow\ \ \ a=3\ \ \ \Rightarrow\ \ \ f(x)=3x\ \ \ \Rightarrow\ \ \ Ans.\ (?)\\\\[/tex]

[tex](6)\ \ \ f(x)=ax^2\ \ \ and\ \ \ f(2)=48\\.\ \ \ \Rightarrow\ \ 48=a\cdot2^2\ \ \Rightarrow\ \ a=48:4=12\ \ \Rightarrow\ \ f(x)=12x^2\ \Rightarrow\ \ Ans.\ C\\\\(7)\ \ \ inversely:\ \ \ f(x)= \frac{a}{x} \ \ \ and\ \ \ f(2)=4\\.\ \ \ \Rightarrow\ \ \ 4= \frac{a}{2} \ \ \ \Rightarrow\ \ \ a=4\cdot2=8\ \ \ \Rightarrow\ \ \ y= \frac{8}{x}\ \ \ \Rightarrow\ \ \ Ans.\ B [/tex]

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