x * (x^2 + 6x + 9) divided by x * (x^2 - 9) which factors to:
x * (x + 3) * (x + 3) divided by x * (x + 3) * (x - 3)
The x in the numerator and denominator cancel out.
The (x + 3) in the numerator and denominator cancel out.
you are left with:
(x + 3) / (x - 3)
that's the simplified equation.
the restrictions come from the original factored equation, which is:
x * (x + 3) * (x + 3) divided by x * (x + 3) * (x - 3)
x in the denominator can't be equal to 0.
x can't be equal to -3, otherwise (x + 3) in the denominator would be equal to 0.
x can't be equal to 3, otherwise (x - 3) in the denominator would be equal to 0.