What is a statement that is true for any number or variable?

What is the missing constant term in the perfect square that starts with x^2 -20x

In exponential growth functions, the base of the exponent must be greater than 1,how would the function change if the base of the exponent were 1? how would the fiction change if the base of the exponent were between 0and 1

If there is 20 dogs in the shelter and 5 dogs get homes, and then 43 more dogs come. how many dogs are there in the shelter?