What is the real number of "a" equals to? What is the real number of "b" equals to?
First, we need to "rationalize" the denominator, but instead of square roots, we use 8i.
-1 - 4i / 8i (8i / 8i)
This is:
-1 - 4i / 8i (8i / 8i) = -1 - 4i ( 8i ) / 8i ( 8i) = - 1 - 4i ( 8i ) / - 8 = - 8i + 32 / - 8 = -8i / -8 + 32 / -8 = -4 + i
Now you should very well know what a and b are.
:)