A line passes through (3,4) and (4,7). A second line passes through (7,9). What is one other point that the second line may pass through if it is parallel to the first line?

1 Answer
Jan 26, 2018

Any point on the line y=3x12 is a viable answer.

Explanation:

Slope formula from two points:

m=y2y1x2x1

Slope of the given line:

m=7443=31=3

The equation of this line using point-slope form:

yy1=m(xx1)

y7=3(x4)

y7=3x12

y=3x5

Since the unknown line is parallel to this one, it has the same slope. Using the newfound slope, we can craft an equation for the new line:

yy1=m(xx1)

y9=3(x7)

y9=3x21

y=3x12

This is the "second line" that the question mentions. Now, we just need to pick a point anywhere on this line by plugging in an x-value and get a y-value back. I'll pick 6 for an x-value:

y=3x12

y=3(6)12

y=1812

y=6

A point on the line is (6,6).