Hi mcaelli,

1)

This is the classic difference of two squares. Use the following model to factor:

2)

For this one, think of two numbers whose product is -5 and whose sum is 4. You'll discover that there is only one solution to that question: 5 and -1

3)

Try expanding everything and collecting terms to get a neat quadratic expression. Then, we'll try to factor it. Or, better still, do what stapel suggests in her post. It's cleaner.

4)

Observe that the expression has a common monomial factor.

5)

This is a strange little booger!

Let x = (9+5), then

Now back substitute to get

I really don't know what you might want to do next since everything here is numbers.