Adding/summing two arrays

Question

I\'ve encountered a purely hypothetical problem which feels like it has an easy solution if I find the right linq method...

I have two arrays of ints and I know they are

Answer 1

Without LINQ:

private static IEnumerable AddArrays(IEnumerable a1, IEnumerable a2)
{
    var e1 = a1.GetEnumerator();
    var e2 = a2.GetEnumerator();

    while (e1.MoveNext() && e2.MoveNext())
        yield return e1.Current + e2.Current;
}