Hi everyone. First of all, congratulations for the forum.
I'm trying to grasp, as a complete beginner, some concepts of Math. I'm reading "Mathematics: its content methods and meaning"
I have a doubt (it won't be the last )
Mathematics: Its Content, Methods and Meaning - Aleksandr Danilovich Aleksandrov, Andréi Nikoláevich Kolmogórov, M. A. Lavrent'ev - Google Libros
I hope the link works, if it doesn't I'll copy the example.
I don't understand the step in page 67
S_{2}=g(t + At)^{2} / 2 = gt^{2}/2 + g/2 (2tAt + At^{2})
It's this part in bold that I don't know where it comes from.
I hope the notation is legible and my English readable.