from math import *

def f(x):
   return x**2 + 2*x + 3 

N = 100
a = 0
b = 2

a = float(a)
b = float(b)
h = ( b - a ) / N
sum = f(a) + f(b)
x = a
for i in range( N-1):
   x += h
   sum += 2 * f(x)

T = sum * h / 2
print "Trapezoid rule approximation:", T