def question11(f, x_0, x_n, h):  
    sum_ = 0    
    x_0 = 1 
    x_n = 2
    n = int((x_n - x_0) / h)
    for i in range (1, n + 1):
        x_i = x_0 + i * h
        sum_ += f(x_i) * h  
    return sum_

def f(x):
    return x / ( x ** 2 + 1) 

question11(f, 1, 2, 0.01)

0.4576443659569775

question11(f, 1, 2, 0.001)

0.45809535593707956

question11(f, 1, 2, 0.0001)

0.4581403658370801

question11(f, 1, 2, 0.00001)

0.4581408659360804

question11(f, 1, 2, 0.000001)

0.4581453159370582

question11(f, 1, 2, 0.0000001)

0.4581453609370471