3. What is the equation of the line in #2?

The line in #2 goes through the points (2, 3) and (4, 1).

First find the slope. Use the formula

which in this case will be

as we saw in #2. At this point, we can use the point slope form of the equation.

y - y1 = m(x - x1)

which becomes

y - 3 = -1 (x - 2)

y - 3 = -x + 2

Add 3 to both sides

y = -x + 5

Note that, if we plug our values for x and y into this equation, we get

(3) = -(2) + 5

and

(1) = -(4) + 5

so both of our points are on the line.