Question

Jordan is trying to derive the formula for the sum of a finite arithmetic series. To do this he decides to add the numbers 1 to 100. He notices that 1 + 100 = 101, 2 + 99 = 101, 3 + 98 = 101, and so on. He knows that he needs to add the first term to the last term. If n is the number of terms in the series, what should he multiply (a1 + an) by?

Answer 1

A)
2n


B)
50


C)

n/2



D)
n

Answer 2

what does "a" and "l"
stands for in the above question?