Slope of the two non vertical lines is .

Replace  in slope formula.

          (Product of two same signs is positive)

Apply multiplication property of equality:If a = b then a c = b c.

(Multiply each side by (2k+2))

        (Cancel common terms)

Distribute terms using distributive property: a( b + c )= ab + ac.

             (Multiply: )

Apply addition property of equality:If a = b then a + c = b + c.

(Add k to each side)

Rearrange the terms using commutative property: a + b = b + a.

      (Apply additive inverse property: )

           (Apply additive identity property: )

                    (Add: )(Add 0.5 to each side)

            (Apply additive inverse property: )

                  (Apply additive identity property: )

                        (Add: )

Apply division property of equality:If a = b then .

                   (Divide each side by 0.5)

                           (Cancel common terms)

                                 (Divide: )

Check:

To check the solution, substitute in .

   (Product of two same signs is positive)

      (Multiply: )

         (Add: )

           (Subtract: )

        (Divide: )

Compare the values, the equation is true.

The value of .