The Riemann sum, lim_Max delta x_1 rightarrow infinity Sigma^n_j = 1 f(* X_i) delta X_i, is equivalent to lim_n rightarrow infinity Sigma^n_j = 1 f(a + I delta x) delta x with delta x = b -a/n. Write the integral that produces the same value as lim_n rightarrow infinity Sigma^n_j = 1 (1 + i3/n) 3/n. integral^3_1 (x + 1) dx integral^4_1 (x) dx integral^4_1 (3x+1) dx integral^3_1 (x) dx