Question

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

Answer 1

Answer:

$y = -\frac{7x}{3} - 24$

Step-by-step explanation:

We can model this function using the equation of a line:

$y = ax + b$

Where a is the slope of the line and b is the y-intercept.

To find the values of a and b, we can use the two points given:

(-9, -3):

$-3 = a * (-9) + b$

$-9a + b = -3$

(-12, 4):

$4 = a * (-12) + b$

$-12a + b = 4$

If we subtract the second equation from the first one, we have:

$-12a + b - (-9a + b) = 4 - (-3)$

$-12a + 9a = 4 + 3$

$-3a = 7$

$a = -7/3$

Then, finding the value of b, we have:

$-12a + b = 4$

$28 + b = 4$

$b = -24$

So the equation is:

$y = -\frac{7x}{3} - 24$