Question

Write a linear equation in point-slope form for the line that goes through (1, -3) and (3,9).

Answer 1

The answer would be six

Answer 2

The slope of the line is 6, meaning that you can eliminate A,C. Since the point slope formula is y-y1=m(x-x1) you just need to see if the points are correct.

B. (3,9)
D. (1,-3)

While these do contain one point, substitute the coordinates to see which contain both.

B.

(1,-3): -3-9=6(1-3): -12=-12
(3,9): 9-9=6(9-3): 0= 6(6)

D.

(1,-3): -3+3=6(1-1): 0=6(0); 0=0
(3,9): 9+3=6(3-1): 12=6(2): 12=12

D is correct since the coordinate are on the line.