Question

Jumlah bilangan kelipatan 4 antara 200 dan 400

Answer 1

204, 208, 212, .... 396
Un = a + (n - 1)b
396 = 204 + (n - 1).4
396 = 204 + 4n - 4
396 = 200 + 4n
196 = 4n
n = 49
Sn = (n/2)(a + Un)
S49 = (49/2) (204 + 396) = 49/2 . 600 = 14.700

Answer 2

204, 208.......396
a = 204
b = 208-204 = 4
Un = 396

Un = a + (n - 1)b
396 = 204 + (n - 1)4
396 = 204 + 4n - 4
-4n = 204 - 4 - 396
-4n = -196
   n = -196/-4
   n = 49

Jumlah bilangan
Sn = n/2 (2a + (n-1) b )
Sn = 49/2 (2.204 + (49-1)4)
Sn = 49/2 (408 + 196 - 4)
Sn = 49/2 (600)
Sn = 14700