4. If f(x) varies directly with x, and f(x) = 45 when x = 9, find the value of f(x) when x = 3.
(Points : 1)
5
9
15
27

Question 5. 5. Which does not show a direct variation between x and y?
(Points : 1)
y = 2x
y = 0.5x
y =
y =

Question

4.  If f(x) varies directly with x, and f(x) = 45 when x = 9, find the value of f(x) when x = 3.
 (Points : 1)  
       5
        9
        15
        27
 
      



Question 5. 5.  Which does not show a direct variation between x and y?
 (Points : 1)  
       y = 2x
        y = 0.5x
        y =  
        y =

jhannybean · Answer

4. $y=kx$ $$y=45~,~x = 9 ~,~ k = \dfrac{y}{x}$$

jhannybean · Answer

After finding k, plug $x=3~,~ k$ back into $y = kx$

jhannybean · Answer

5. direct variation : $y=kx$
    indirect variation: $y = \dfrac{k}{x}$