No.2 Sum of the even-valued terms in the Fibonacci

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

A:
#method1
a = 1
b = 1
c = a + b
result = 0
while (c < 4000000):
    result += c
    a = b + c
    b = c + a
    c = a + b
print "result=%d" %result

#method2

x = y = 1
sum = 0
while (sum < 4000000):
sum += (x + y)
x, y = x + 2 * y, 2 * x + 3 * y
print sum