If ab + c = a(b + c), which of the following must be true?
Select:
A) x = 0 and z = 0
B) x = 1 and y = 1
C) y = 1 and z = 0
D) x = 1 or y = 0
E) a = 1 or c = 0
ab + c = ab + ac   c = ac   case 1: c not= 0, a = c/c = 1   case 2: c = 0, 0 = a0 = 0   Combining 2 cases: a = 1 or c =0   E. is the answer.
<result>E</result>
If ab + c = a(b + c), which of the following must be true?