Jawabanmu

2014-01-27T22:30:58+07:00
Sn = U1 + U2 + U3 .....+ U50 
Sn = a + (a+b) + (a+2b) + .... 
a / U1 = 2x + 1
Sn = 4725 
n = 50 
b = U2 - U1
b = (2x + 2) - (2x +1)
b= 1

Rumus Sn = n/2 (2a + (n-1) b) 
4725 = 50 / 2 (2 (2x + 1) + (50 - 1) 1)
4275 = 25 ( 4x +2 + 49)
4275 = 25 ( 4x + 51) 
4275 = 100x + 1275
4275 - 1275 = 100x
3000 = 100x 
30 = x