Hello everybody, I'm trying to understand some steps in the evolution of calculus, and in a .pdf found in the internet I read the document: http://www.ugr.es/~mmartins/old_web/Docencia/Old/Docencia-Matematicas/Historia_de_la_matematica/clase_3-web.pdf [Broken], in pags. 14-15. I want to solve the to equations of the two areas (1/ar) and (r/a), but I when I try solving the infinite sum inside the symbols: Ʃ, for example, with the first term for 1/r^k for k=0 equal to 1, I don't reach the same resoult (1/ar). So anybody can help me to understand this, and why lastly the area isn't 1/ar nor r/a, but 1/a as Fermat proved. Thank you all.