Exercise
What are the integer solutions of 7x + 3y = 0?
x = 3n, y = 7n, with n in Z
x = 7n, y = -3n, with n in Z
x = -3n, y = 7n, with n in Z
No, try n = 1 and find a counterexample
No, try n = 1 and find a counterexample
Yes!