" Life is not a problem to be solved but a reality to be experienced! "
© Copyright 2013 - 2024 KUDO.TIPS - All rights reserved.
105, 110, 115..... 295
Un = a + (n-1) b
295 = 105 + (n-1) 5
295 = 105 + 5n- 5
295- 105 + 5 = 5 n
195 = 5 n
39 = n
Sn = n / 2 ( 2 a + (n-1) b)
Sn = 39/2 ( 2 × 105 + 38 × 5)
Sn = 39 /2 ( 210 + 190)
Sn = 39 / 2 (400)
Sn = 39 × 200
Sn = 7800
Smg mmbnt