Question

(x + y)totul la a doua 

Answer 1

$(x+y)^{2} = (x+y)*(x+y) =$
=$x^{2} + x*y+y*x + y^{2} = x^{2} + y^{2}+2*x*y$

Answer 2

(x+y)^2 = (x+y)(x+y) = x^2 + xy + xy + y^2 = x^2 +2xy + y^2