If α,β are the zeros of the polynomial x2 - px + 36 and α2+β2 = 9, then what is the value of p?
±6
±3
±8
±9
Here a = 1, b = -p, c = 36. α+β=−ba=p αβ=ca=36 α2+β2=(α+β)2 - 2αβ ⇒ p2−2×36=9 ⇒p2=81 ⇒p=9 or −9