1. The problem statement, all variables and given/known data Determine a line that is tangent to both f(x)=x2 and g(x)=x2-2x 2. Relevant equations 3. The attempt at a solution f(x)=x2 => f'(x)=2x g(x)=x2-2x => g'(x)=2x-2 f'(a) = f'(b) 2a = 2b-2 I don't know how to continue. Thanks for help.