... f(0,0,0)x1x2x3 + f(0,0 ,1) x1x2 x3 + f(0,1,0)x1x2x3 + f(0,1 ,1) x1 x2 x3 + f(1,0,0) x1x2x3 + f(1,0,1)x1x2 x3 + f(1,1,0) x1 x2x3 + f(1,1 ,1) x1 x2 x3 Vỏỷy ... x2+x3].[f(0,0 ,1)+ x1+x2+x3]. [f(0,1,0)+x1+x2+x3].[f(0,1 ,1)+ x1+x2+x3]. [f(1,0,0)+x1+x2+x3].[f(1,0 ,1)+ x1+x2+x3]. [f(1,1,0)+x1+x2+x3].[f(1,1 ,1)+ x1+x2+x3] ... = f(0). x + f (1). x Kóỳt luỏỷn: Duỡ laỡ f(x) = x, f(x) = x hay f(x) = , ta õóửu coù daỷng: f(x) = f(0).x + f (1). x Vỏỷy f(x) = f(0).x + f (1). x trong õoù f (0), f (1) õổồỹc goỹi laỡ...