如果w，x，y，z是布尔变量，那么正确的是以下哪一项?
(A) wx + w(x + y)+ x(x + y)= w + xy
(B) (wx’(y + z’))’+ w’x = w’+ x + y’z
(C) (wx’(y + xz’)+ w’x’)y = xy’
(D) (w + y)(wxy + wyz)= wxy + xyz答案： (B)
说明： (A)
wx + w(x+y) +x(x+y)
= wx + wx + wy + x + xy
= wx + wy + x + xy
= x(w + y + 1) + wy
= x + wy
(B)
(wx’(y + z’))’ + w’x
= w’ + w’x + y’z
= w’ + x + y’z
(C)
(wx’(y + xz’) + w’x’)y
= wx’y + wx'xz'+ w’x’y
since x'x = 0
= wx’y + w’x’y
= x’y(w + w')
= x’y
(D)
(w + y)(wxy + wyz)
= wxy + wyz(w + y)(wxy + wyz)
= wxy + wyz
因此，选项(B)是正确的。这个问题的测验