© 2014 Shmoop University, Inc. All rights reserved.
Derivatives

Derivatives

Tangent Line Approximation

There are only two things we need to remember about the tangent line to f at a.

  • The tangent line and f have the same y-value at a.  
      
    That is, the point (a,f(a)) is on f and also on the tangent line to f at a.

  • The tangent line and f have the same slope at a.  
      
    That is, the slope of the tangent line to f at a is f'(a).

Advertisement
Advertisement
Advertisement