def somatorio(x, y):
    soma = 0
    while x <= y:
        soma += x
        x += 1
    return soma
 
print(somatorio(1, 2))
print(somatorio(1, 5))
 
def somatorio_2(x, y): # usa a fórmula da soma da P.A.
    return (x + y) * (y - x + 1) // 2
 
print(somatorio_2(1, 2))
print(somatorio_2(1, 5))
 
def somatorio_3(x, y): # usando coisas prontas da linguagem
    return sum(range(x, y + 1)) # um range não inclui o valor final, por isso soma 1 ao y
 
print(somatorio_3(1, 2))
print(somatorio_3(1, 5))
 
 

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