Question

Which line has an equation of y=-5x+4 in slope-intercept form?

a line passing through the points (1, 9) and (3, 19)
a line passing through the points (2, –14) and (4, –24)
a line passing through the points (1, 1) and (3, 11)
a line passing through the points (2, –6) and (4, –16)

Answer 1

You can figure the line for each pair of points, or you can try the points in the equation you have and see which are on the line.

First answer: x=1, y=-5×1 +4 = -1 . . . not 9. (1, 9) is not a point on the line

Second answer: x=2, y=-5×2 +4 = -6 . . . not -14. (2, 14) is not a point on the line

Third answer: (see the calculation for the first answer) . . . -1 ≠ 1. (1, 1) is not a point on the line

Fourth answer: (see the calculation for the second answer) We know that (2, -6) is on the given line. Checking (4, -16), we find it is as well.

The appropriate choice is the 4th answer:

... a line passing through the points (2, -6) and (4, -16)