如果 w、x、y、z 是布尔变量，那么以下哪项是正确的?
(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：(乙)
解释：(一)
wx + w(x+y) +x(x+y)
= wx + wx + wy + x + xy
= wx + wy + x + xy
= x(w + y + 1) + wy
= x + wy
(乙)
(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
(四)
(w + y)(wxy + wyz)
= wxy + wyz(w + y)(wxy + wyz)
= wxy + wyz
所以，选项(B)是正确的。这个问题的测验