
Antonia E.
asked 12/05/21Hurry and answer please
Which equation represents the line passing through the points (3, 2) and (–9, 6)?
[A] x – 3y = 9
[B] x + 3y = 9
[C] 3x – y = -9
[D] 3x + y = 9
Explain your thinking.
2 Answers By Expert Tutors

Natalie K. answered 12/06/21
High School Math Teacher with 14 Years Tutoring Experience
First, we must calculate the slope using the formula, m = (y2 - y1) / (x2 - x1).
Let x1, y1 = (3, 2) and x2, y2 = (-9, 6)
m = (6 - 2) / (-9 - 3) = 4 / -12. This can be reduced to -1/3.
Now, we plug in the point x1, y1 = (3, 2) and slope m = -1/3 into the point slope formula: y - y1 = m (x - x1).
y - 2 = (-1/3)(x - 3)
Distribute the slope to (x-3):
y - 2 = (-1/3)(x) + 1
Add two to both sides:
y = (-1/3)(x) + 3
The equation must be in standard form (Ax + By = C, where A, B, and C are NOT fractions) so let's add (1/3)x to the other side:
(1/3)x + y = 3
Multiply both sides of the equation by 3 to get rid of the fraction:
x + 3y = 9

Mark M. answered 12/06/21
Mathematics Teacher - NCLB Highly Qualified
If points are on a line then the coordinates of each point must solve the equation. For which equation does the two pairs of coordinates solve?
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Mark M.
Did you test the two pairs in each equation?12/06/21