Kaka Kaka ada yg tau jawabannya gak?

1. Un = a + (n - 1)b
U100 = 2 + (100 - 1)2
U100 = 2 + (99 × 2)
U100 = 2 + 198
U100 = 200

2. Un = a + (n - 1)b
99 = 1 + (n - 1)2
99 = 1 + 2n - 2
99 = -1 + 2n
100 = 2n
n = 50

Sn = n/2 ( 2a + (n - 1)b)
S50 = 50/2 (2 × 1 + (49 × 2))
S50 = 25 (2 + 98)
S50 = 25 × 100
S50 = 2500

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