If 2p + 5q = 12 and pq = 3, find the value of 4p2 + 25q2.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 84.
4p2 + 25q2
= (2p)2 + (5q)2
= (2p + 5q)2 - 2(2p)(5q)
= (2p + 5q)2 - 20pq
= 122 - 20 × 3
= 144 - 60
= 84