a) If x is 2, y is 8, and z is 4, then what is the value of the formula?

b) If the parenthesis are omitted, what is the value of 2x + y / z -2.

c) What's the purpose of the parenthesis?

2) Which of the following expressions are wffs (well-formed formulas)?

a)

b) ((A (B'))

c) )

d)

3) Use a truth table to show that is a tautology.

A	B
T	T
T	F
F	T
F	F

4) If P and are true, then what can you infer?

5) If Q' and are true, then what can you infer?

6) Justify each step in the proof sequence of

1. A'

2. B

3.

4.

5.

6.

7. C

7) Using propositional logic, prove the validity of the argument

8) Deduction method: For a valid argument of the form

,

we can prove

instead.

Why?