Recent content by bananaman13

Thank you so much. So, in which case, Sn=n/2 (A1+An) is still equal to Sn=n/2 [2A1+(n-1)d] Just different in how to solve it.

I don't understand on how to get the answer of a certain problem in arithmetic series. formula/s: Arithmetic means An=A1+ (n-1)d Arithmetic series Sn=n/2 (A1+An) I understand on how to get the terms to these but when finding for: Find A1 if, S10= -20 , d= 4 & Find S12 if, 2+5+8+... I...