Jawabanmu

2014-03-31T20:54:22+07:00
A=3 , b=5

s50 = n/2 (2a+(n-1)b)  
      = 50/2 (2(3) + (50-1)5)
      = 25 (6+ 49.5)
      = 25 (6 + 245)
      = 25 . 251
      = 6275
2014-03-31T20:56:16+07:00
A=3 b=5
n=50

Sn = 1/2 n (a + Un)
.....= 1/2 n (a + a + (n-1)b)
.....= 1/2 n (2a + (n-1)b)
S50 = 1/2. 50 (2.3 + 49.5)
.......= 25 x (6 + 245)
.......= 25 x 251
S50 = 6.275