What are the values of k when the line of y equals kx -2 is a tangent to the curve of y equals x squared -8x plus 7?

If: y = kx -2 and y = x^2 -8x+7

Then the values of k work out as -2 and -14

Note that the line makes contact with the curve in a positive direction or a negative direction depending on what value is used for k.