A 3-line to 8-line decoder is connected as shown. Where x, y and z are inputs (z is the least significant input digit) and F is an output. Which of the following expressions correctly describes F?

F(x,y,z) = z
F(x,y,z) = x
F(x,y,z) = z'
F(x,y,z) = yz
F(x,y,z) = x'

1 is WRONG. Hint: Use the generic symbol of the NAND gate (OR symbol with bubbles on inputs) to see that the combination of the decoder and NAND gate sums minterms m3 + m7. Here is the circuit you should use:

          __________ 

          |        | 

          |       0|O-- 

          |       1|O--  (Cancel bubbles)

       x--|C      2|O--       ______ 

       y--|B      3|O--------O\     \ 

       z--|A      4|O--        )     )----F(x,y,z) 

          |       5|O--   +--O/_____/ 

       1--|E      6|O--  |

          |       7|O-----+ (Cancel bubbles)

          |________|

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