摘要： We know that: a = first termr = common ration = number of terms We'r going to use a notation $S_n$ to denote the sum of first n terms as following: $S 阅读全文

摘要： Quadratic Formula: The quadratic equation is as follows: $ax^2+bx+c=0$ The quadratic formula tells us that the solutions to this equation is $x = \fra 阅读全文