### Home > CALC > Chapter 3 > Lesson 3.4.3 > Problem 3-177

3-177.

Write a Riemann sum to estimate

*A*(*g,*0 ≤*x*≤ 2) for*g*(*x*) = −*x*^{2}+ 4 using*n*left endpoint rectangles. Homework Help ✎Then calculate for

*n*= 20.How can you use your result to estimate

*A*(*g*, −2 ≤*x*≤ 0)?*A*(*g*, −2 ≤*x*≤ 2)?

General left-endpoint Riemann sum:

Substitute.

Consider the shape of the graph of *g*(*x*).