inferences

Question 1

if A then B
A
—
B

Answer 1

modus ponens (valid)

Question 2

if A then B
B
—
A

Answer 2

affirming the consequent (invalid)

Question 3

if A then B
Not B
—
Not A

Answer 3

modus tollens (valid)

Question 4

if A then B
not A
—
not B

Answer 4

denying the antecedent (invalid)

Question 5

A

Answer 5

double negation elimination (valid)

Question 6

A or B or C 
not A 
not B 
---
C

Answer 6

disjunctive syllogism (valid)

Question 7

A or B 
if A then C 
if B then C 
---
C

Answer 7

disjunction elimination (valid)