Misalkan p=3-√5 dan q=3+√5. Hitunglah 2pq

Diket :
p = 3+√5
q = 3+√5

Jawab :
2pq
= 2((3-√5)(3+√5))
= 2(9-5)
= 2(4)
= 8

p = 3-√5
q = 3+√5

catatan :
(a - b) (a + b) = a² - b²

jadi
2pq
= 2(3-√5)(3+√5)
= 2 (3² - (√5)²)
= 2 (9 - 5)
= 2 (4) 
= 8