" Life is not a problem to be solved but a reality to be experienced! "
© Copyright 2013 - 2024 KUDO.TIPS - All rights reserved.
225 = 1+2n-2
n = 112
S112 = 56 × 226 = 12656
Sn = n/2 (2a+ (n-1) b)
225 = n/2 (2•1 + (n-1) 2)
225 = n/2 (2n)
225 = 2n^2/2
225= n^2
n= 15
U15 = a + 14b
= 1 +28 = 29