jika 6+8+10+12+....+40=60p-6 maka nilai p

Pakai rumus deret aritmatika,
a = 6
b = 8 - 6 = 2

Un = a + (n - 1)b
40 = 6 + (n - 1) 2
40 - 6 = (n-1)2
34 = (n - 1)2
34/2 = n - 1
17 = n - 1
n = 18

Sn = n/2 ( a+ Un)
S18 = 18/2 (6 + 40)
S18 = 9(46)
S18 = 414

414 = 60p - 6
414 + 6 = 60p
60p = 420
p = 420/60
p = 7

Bab Pola Bilangan
Matematika SMP Kelas VII

6 + 40 = 46
8 + 38 = 46
10 + 36 = 46
12 + 34 = 46
14 + 32 = 46
16 + 30 = 46
18 + 28 = 46
20 + 26 = 46
22 + 24 = 46
               ------- +
                414
 
414 = 60p - 6
60p = 414 + 6
p = 420 / 60
p= 7