Jumlah bilangan kelipatan 4 antara 100 dan 300 adalah
Jawab :
Antara 100 ...... 300
104 + ...... + 296
b=4
Un = a + (n-1) b
296 = 104 + (n-1) 4
296 = 104 + 4n - 4
296 = 100 - 4n
4n = 296 - 100 = 196
n = 196/4 = 49
Sn = n/2 (U1 + Un)
S49 = 49/2 ( 104 + 296 )
= 49/2 × 400
= 9800
104 + ...... + 296
b=4
Un = a + (n-1) b
296 = 104 + (n-1) 4
296 = 104 + 4n - 4
296 = 100 - 4n
4n = 296 - 100 = 196
n = 196/4 = 49
Sn = n/2 (U1 + Un)
S49 = 49/2 ( 104 + 296 )
= 49/2 × 400
= 9800
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