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* - *y*_{1} = *m*(*x - x*_{1})

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.