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

Answers:

1. If a and b are real numbers, then (a+b)(a-b) = a² + b²
   x and y are real numbers.
     (x+y)(x-y) = x² + y²
   
   
   
2. Any odd integer x can be written in the form x = 2k + 1 for some integer k.
   y is an odd integer.
    y = 2k+1 for some integer k.
   
   
   
3. All dogs wag their tails.
   An Irish wolfhound is a type of dog.
     All Irish wolfhounds wag their tails.
   
   
   
4. If an animal is at the top of the food chain, then it is carnivorous.
   Tigers are at the top of the food chain.
     Tigers are carnivorous.