x+y=6 এবং x-y=4 হলে xy এর মান কত?
A
4
B
5
C
6
D
3
Correct Answer: 5
xy = {(x + y)/2}² - {(x - y)/2}² = (6/2)² - (4/2)² = (36/4) - (16/4) = 9 - 4 = 5