If $f(x) = x^2 + 7x$, calculate the value of: 

1. $f(2)$ 

2. $f(-3)$ 

3. $f(i)$ 

4. $f(-3.5 + 1.5i)$ 

   Answer (d):

   $x = -14.5$

5. $x$ if $f(x) = 0$. 

   Hint (e):

   Factor $x^2 + 7x = 0$ then use the Zero Product Property.

   Answer (e):

   $x = 0$ and $x = -7$