If (x+2y)=a and (x-2y)=b, which of the following expression is equal to xy?
সমাধান
সঠিক উত্তর: Option C
x+2y = a
x-2y = b
Adding above two eauations, x = a+b/2
Subtracting above two equations, y = a-b/4
so, xy = (a+b)/2 + (a-b)/4 = (a+b) (a-b)/8 = (a2 - b2)/8
