I asked this question a few minutes ago and someone said it is a duplicate to this but it is not. I want a modern proof!
closed as unclear what you're asking by goldPseudo♦ Apr 3 '17 at 8:01
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.