We can factor an a from ax and ay so we have a times x plus y. We can also
factor a 2 from 2x and 2y. So we'll have plus 2 times x plus y. And notice if we
were to just distribute we'd get back with what we started with. But in this
line there's something incredible happening. This would be one term made up of
two factors a times x plus y. This would be another term made up of two factors,
2 and x plus y. So do you see it? What's the common factor for each of these
terms? Write your answer here.