x+y=4,x-y=2 হলে xy এর মান -
সমাধান
সঠিক উত্তর: Option C
x+y=4.......(i)
x-y=2........(ii)
∴ xy= {(x+y)/2}² -{(x-y)/2}²
= (4/2)²-(2/2)²
= 2²-1²
= 4-1
= 3
x-y=2........(ii)
∴ xy= {(x+y)/2}² -{(x-y)/2}²
= (4/2)²-(2/2)²
= 2²-1²
= 4-1
= 3
