---------Do the multiplication and see what happens.
, which is your left member.
What happens if you work from the right member using the same variable assignments? , which is the right member; and is the SAME result as when simplifying the left member.
We did not need to know where the 4ab, or 4*alpha*beta, came from. We just wanted to find out if the left and right members are equal. Yes, they are equal.