a+b = 5 এবং a-b = 3 হলে ab এর মান কত?
A
4
B
6
C
8
D
12
Correct Answer: 4
a + b = 5a - b = 3ab = (a+b/2)2 -(a-b/2)2 = (5/2)2 - (3/2)2 = 25/4 - 9/4 = 16/4 = 4