Jawabanmu

2014-02-14T20:43:37+07:00
Sn =  \frac{n}{2} (2a + (n-1)b)
a = 2x +1
n = 50
b = 1
S50 = 25(2(2x + 1) + 49)
4275 = 25(4x + 51)
171 = 4x + 51
4x = 120
x = 30

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