jika (2p + 1) (9p-2) (6p+15) dan (5k-2) adalah empat suku pertama barisan aritmatika maka nilai p+k

jawab
barisan aritmetika

u1 = 2p +1
u2 = 9p-2
u3 = 6p + 15
u4 = 5k - 2
..
(i)  2U2 = u1 + u3
2(9p -2) = 2p+1 +  6p+ 15 
18 p - 4 = 8p + 16
10p = 20
p= 2

(ii)
2U3 = u2 + u4
2(6p + 15) = 9p - 2 + 5k  - 2
12p + 30 = 9p + 5k - 4
12p - 9p + 30 + 4 = 5k
3p + 34 = 5k

k = 1/5 ( 3p+34)
k = 1/5 (3. 2 + 34)
k = 1/5 (40)
k = 8

nilai p+ k = 2+ 8 = 10