Answer:

Explanation:
To factor the expression y⁴ + 40y² + 400 completely over the complex numbers, we can use a substitution to simplify it.
Let z = y². Then the expression becomes:
z² + 40z + 400
Now, factor this quadratic expression:

We have formula: (a+b)² = a²+2ab + b², Using this, we get

Now, substitute back the original variable:

So, the factored expression over the complex numbers is:
