Is #100 - 20y + y^2# a perfect square trinomial and how do you factor it?
Yes, your expression is a perfect square trinomial.
A trinomial is simply a polynomial that has three terms. Your expression is a trinomial because it has three terms:
In order for it to be a perfect square trinomial, it has to be equal to the square of a binomial, which is a polynomial that has two terms.
You can factor your expression in order to check if it meets this criterion. A trinomial can be factored as a product of two binomials, so all you have to do is see if these two binomials are equal
The right side of this equation is equal to
Now match the terms of your original expression with these terms
You need to have
This solution is not valid because the expression would be equal to
This is a valid solution, since
Therefore, your original expression is a perfect square trinomial because you can write it as