Using universal modus ponens or universal instantiation, fill in the following

1. If a and b are real numbers, then (a+b)(a-b) = a² + b²
   x and y are real numbers.
   _______________________________________________
   
   
   
2. Any odd integer x can be written in the form x = 2k + 1 for some integer k.
   _________________________________________________
    y = 2k+1 for some integer k.
   
   
   
3. All dogs wag their tails.
   An Irish wolfhound is a type of dog.
   _______________________________________________
   
   
   
4. If an animal is at the top of the food chain, then it is carnivorous.
   _________________________________________________
     Tigers are carnivorous.