Jawabanmu

2014-02-14T09:36:39+07:00
B = 1 ; a = 2x+1 ; Un = 2x + 50 ; Sn = 4275

Un = a + (n-1)b
2x+50 = 2x+1 + (n-1)1
49 = n-1
50 = n
n = 50

Sn =  \frac{1}{2} n (a+Un)
 S_{50}  \frac{1}{2} 50 (2x+1 + 2x+50)
4275 = 25 (4x+51)
171 = 4x+51
120 = 4x
30 = x
x = 30
2 4 2