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Home > CALC > Chapter 7 > Lesson 7.4.1 > Problem 7-177

7-177.
  1. Given: f(x) = 5x4 − 3x2 Homework Help ✎

    1. Write the equation of the tangent line to f(x) at x = 1.

    2. Use your tangent line to approximate f(1.1).

    3. Is the approximation an over or under estimate of the actual value?

Use point-slope form of a line. f(1) will give you the point, and f '(1) will give you the slope.

Since a linear equation is easier to evaluate than a 4th-degree polynomial, use the tangent line to approximate f(1.1).

Is the graph of y = f(x) concave up or down x = 1?