F(x1;x2)=(x1+!x1)+(!x2+!x2) = 1 + !x2 = 1
F(x1;x2)=(x1+x2)+(!x1+!x2) = x1+x2+!x1+!x2 = 1 + 1 = 1
F(x1;x2)=x2+!x2+x1 = 1+x1 = 1
F(x1;x2)=x1+x1+!x1+x2+!x2 = x1+1+1 = 1
F(x1;x2)=x1*x2+x1*!x2+x2*!x2 = x1*(x2+!x2)+0 = x1*1 = x1
F(x1;x2)=x1+x2*!x1+x2+x2*!x2 = x1+x2(!x1+1)+0 = x1+x2*1 = x1+x2