There is nothing wrong with Arlene's math. Her answer is correct. The mistake is that she has cited the "associative property" where the "commutative property" should have been cited, and vice versa.
The associative property has to do with where you put parentheses. The commutative property has to do with what order the operands are in.
Answer:
Step-by-step explanation:
the directrix is y=-1
I don't know what the vertex focus is.
