### Home > APCALC > Chapter 5 > Lesson 5.5.1 > Problem 5-155

5-155.

Let .

Write the equation of the line tangent to

.Use the slope, which is

, and the pointto write the equation. Use your tangent line to approximate

.Is the approximation an overestimate or an underestimate of the actual value?

If

is concave up at, then the approximation is an underestimate.