Given: $f(x) = 5x^4 − 3x^2$

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

   Hint (a):

   Use point-slope form of a line. $f(1)$ will give you the point, and $f^\prime(1)$ will give you the slope.

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

   Hint (b):

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

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

   Hint (c):

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