If ( p + q ) = √13 and ( p – q ) = √5 then the value of pq is –

WBBSE – 2019

Solution:

Given that

p + q = √13

Squaring both sides, we get

( p + q )² = 13

( p – q )² + 4 pq = 13

( √ 5 )² + 4pq = 13

5 + 4pq = 13

4pq = 13 – 5

4pq = 8

pq = 8/4

pq = 2

The required answer is ( a ) 2