1. The problem statement, all variables and given/known data The teacher proposed a problem today during a math session. He gave the function : f(x) = x2-6x+5 - and a point P(4,-6). Our mission was to find two tangents for the given point. I thought it was easy, just differentiate the function, and insert the differentiate function for a in : y=a*x + b. 2. Relevant equations function : f(x) = x2-6x+5 differentiate : f'(x) = 2x-6 tangent: y= (2x-6)*x + b tangent eq: -6= (2x-6)*4 + b 3. The attempt at a solution Given the last tangent equation, my plan was to find the two b's, where the tangents met the y-axis. But I failed. Any thoughts?