Final answer:
To find -3z for z = -5 - 9i, multiply both the real and imaginary parts of z by -3, resulting in 15 + 27i.
Step-by-step explanation:
The student asked to write the number -3z where z = -5 - 9i in a + bi form. To find this, we multiply both parts of z by -3:
-3 * (-5 - 9i) = 15 + 27i
So, written in a + bi form, -3z is 15 + 27i.