Given two real numbers p and q such that 1/p + 1/q = 1 and pq = 9, what is p + q?
Given 1/p + 1/q = 1
Multiply both sides by pq pq • (1/p + 1/q) = pq
pq/p + pq/q = pq
q + p = pq
Given pq = 9
Therefore p + q = 9
