(a+b)=√7, (a-b)=√5 হলে,8ab(a²+b² ) এর মান কত?

A 24

B 28

C 32

D 40

Correct Answer: Option A

8ab(a²+b² )
=4ab.2(a²+b² )
={(a+b)²-(a-b)²}{(a+b)²+(a-b)²}
={(√7)²-(√5)²}{(√7)²+(√5)²}
=(7-5)(7+5)
=2×12
=24