Practice question · Select all that apply
Consider the three-input function (A AND B) OR (NOT C). Evaluate it on each row below and select every row where the output is 1.
Hints
- The whole expression is an OR, so it is 1 as soon as either half is 1, check the NOT C half first, since it is quicker.
- Every row with C = 0 is already satisfied; among the rows with C = 1, only the AND term can rescue them.
Show the answer
- A. A = 1, B = 1, C = 0
- D. A = 1, B = 1, C = 1
- E. A = 0, B = 0, C = 0
Why
Rows 1 and 3 have C = 0, so NOT C is 1 and the OR is satisfied regardless of A and B. Of the rows with C = 1, only the last has both A and B equal to 1. The trap is row 4, where a 1 appears among the inputs but neither half of the expression is satisfied, an OR needs a whole term to be true, not merely a true input somewhere.
Practise Truth Tables and Logical Equivalence
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