### Home > CALC > Chapter 12 > Lesson 12.2.3 > Problem 12-90

12-90.

Examine the integral

. Homework Help ✎ Explain why this integral cannot be evaluated exactly using any of our integration tools.

Estimate

, using a Riemann sum with 5 left-endpoint rectangles. Use a substitution in the expansion of

*f*(*x*) =*e*to get a 6^{x}^{th}degree polynomial approximation of. Estimate

using the polynomial of part (c). How could we have improved our answers to parts (b) and (d)?

Use more ________.