Did you clicked 'Cheer up'? That's good. The secret behind the questions is that Lv.13 is 3rd grade ones,and 14 is in high school ones. Combination and permutation. Lv.15 is a high school one called, 'equations of a circle'. Actually,the answer? There's no answer because the question is wrong. The two geometrical shapes never cross each other. You saw how I do it.(Hope that you understand it. If you're studing math with books,then there will be this part on the book you learn.) And,I have to admit that how did I thought that all the students of Seoul would learn high school math,ahead of me. But,if this is an insult to you,then I apologize. I finished High school-1st grade,and doing 2nd grade(a radical root and log) since 2 months ago. I'm going far ahead than my classmates,so I usually have class with the 3rd graders,but most of them are behind me,when they were ahead of me only a year ago. But there are two 3rd graders who are ahead of me(doing trigonometrical function),they are too fast for me to catch up. (I go to math academy on Mon,Tue,Wed,Thu. On Tue and Thu, I go to academy to study myself and teach other 2nd graders.) Actually,D is in a(x^2)+bx+c=0(a quadratic equation),it's b^2-4ac. In the official equation solving one,the D means a lot. If it's +,then there are two numbers that could benefit. If it's 0,tuen there's one,and if it's -,there's nothing(or in high school,use imaginary numbers). You do know that,right?(you did learn it faster than the high-equations) Right now,I'm not doing the 2nd grade one offline,but online in m**astudy. In academies,I'm reviewing functions with strange graphs(high school-2nd term). I start exam studies just a month before exams. My average last term was 97.125,so I hope I get more than 98. (97 was a impossible number in my class,and I was the only one,by 1 question,to cross it. But,information keeps dragging my score back. If it wasn't for that,my average score would be almost 99. 692÷7=98.85.) So,I hope I could get at least 97 to 98. And by the way,I will enter the speech contest,but voices matter,and I don't have it. And,I'm making a script,but I think this is quite hard. I don't think I could fill 3 minutes! So,I have to put more of my efforts to succeed. Well,time for lunch!(I'm in online) Bye!
P.S. When is your final exam? It's usually an early December. And,I think I'll be busy for the whole November. So,if I wrote my last LMA5 novel in October,me too are off. (Of course,I made a lot of novels already,so in November,there are just less ones,but I'll update what I already wrote this month. It's just that there are less ones to be uploaded,because I would stop writing,and update the ones that I already wrote.)