∫20ex dx
∫20 ex dx a=0 and b=2∴h=b−an⇒nh=2 and f(x)=exNow,∫20ex dx=limh→0 h[f(0)+f(0+h)+f(0+2h)+...+f0+(n−1) h]∴ I=limh→0h[1+eh+e2h+...+e(n−1)h]=limh→0h=limh→0h[1.(eh)n−1eh−1]=limh→0h[enh−1eh−1]=limh→0h(e2−1eh−1)=e2limh→0heh−1−limh→0heh−1=e2−1=e2−1