Question 13249
You're right - you use the distance formula for this.  {{{D = sqrt((x2 - x1)^2 + (y2 - y1)^2)}}}.  You know one point, the x-coordinate of the other point, and the distance between the two points.  When you plug this information into the equation, you get {{{5 = sqrt((2 - 2)^2 + (y2 - -1)^2)}}}.  To get rid of the square root, sqare both sides to get {{{25 = (2-2)^2 + (y2 - -1)^2}}}.  Work out the subtraction in the parentheses and then square the answers to get:  {{{25 = y2^2 + 2y2 + 1}}}.  Move the 25 over to get {{{y2^2 + 2y2 - 24 = 0}}}.  Factor this out to get {{{(y2 + 6) (y2 - 4) = 0}}}.  Your two points are (2,-6) and (2,4).