The simplified form of (7x + 4y)2 + (7x − 4y)2 is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 98x2+32y2
We know that (a + b)2 = a2 + 2ab + b2 , and
(a - b)2 = a2 - 2ab + b2
Thus, (7x + 4y)2 = 49x2 + 56xy + 16y2 ----------(i)
(7x - 4y)2 = 49x2 - 56xy + 16y2 ---------------------(ii)
Thus, by adding equations (i) and (ii) we get
⇒ 98x2 + 32y2