Using definite integration as the limit of a sum, $\int_1^2 (2x + 5)\,dx$ equals:
- $6$
- $8$
- $10$
- $12$
Show answer and solution
Correct answer: B. $8$
**Direct evaluation:** $[x^2 + 5x]_1^2 = (4 + 10) - (1 + 5) = 14 - 6 = 8$.
(The limit-of-sum approach in the textbook yields the same: $\lim_n h\sum(7 + 2rh) = 7(1) + (1)(1+0) = 8$.)