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A direct variation function contains the points (–9, –3) and (–12, –4). Which equation represents the function?

y = –3x
y = – x/3
y = x/3
y = 3x

C is the correct answer.

Respuesta :

carlosego

Answer: third option.

Step-by-step explanation:

By definition, a direct variation function has the form shown below:

[tex]y=kx[/tex]

Where k is a constant.

Then, knowing the given points, you can calculate k with the formula for calculate the slope of a line:

[tex]m=\frac{y_2-y_1}{x_2-x_1}=\frac{-4-(-3)}{-12-(-9)}=\frac{1}{3}[/tex]

Substituting k into  [tex]y=kx[/tex], you obtain:

[tex]y=\frac{1}{3}x\\\\y=\frac{x}{3}[/tex]

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