## crystal1 3 years ago “All dogs are mammals.” Which of these is a logically equivalent statement? All animals that are not dogs are not mammals. If it is not a dog, it is not a mammal. All dogs are furry. If it is not a mammal, it is not a dog.

1. zzr0ck3r

ok does the first one make sense? "all animals that are not dogs are not mammals". Hint: cats are not dogs, but they are mammals.

2. meowandwow

The last one is the best choice ^.^ Because dogs are mammals.

3. crystal1

thnks

4. Directrix

An implication and its contrapositive are logically equivalent. As an implication, All dogs are mammals" can be written as If an animal is a dog, then the animal is a mammal. The contrapositve of that statement is: If the animal is not a mammal, then the animal is not a dog. ------- Answer: If it is not a mammal, it is not a dog. is logically equivalent to the given statement. Suggestion: Go to the following link and study a bit about implications: http://www.regentsprep.org/Regents/math/geometry/GP2/PracRC.htm

5. zzr0ck3r

right, you should check those out. then all you have to remember is if P implies Q then, not Q implies not P. it will make life easy:) note: here we have P = its a dog and Q = its a mammal