find tangent equation ( y=x^2 and y=x^2-4x+5) have common tangent.
2. Calculate the equation of the tangent in T at the first parabola:
3. Calculate the point of intersection ofthe tangent and the second parabola:
4. The tangent of the first parabola is tangent to the second parabola too if the radical equals zero:
5. Therefore the equation of the common tangent is: