Add four to negative 𝑖.
We’ve been given a real and an
imaginary number. And we’re looking to find their
sum. What this question is really asking
us to do is to form a complex number. Remember, a complex number, 𝑧, is
of the form 𝑎 plus 𝑏𝑖, where 𝑎 and 𝑏 are both real numbers and 𝑎 is the real
component of 𝑧 and 𝑏 is the imaginary component.
Now if we add four to negative 𝑖,
we get four plus negative 𝑖. But we can actually write this as
simply four minus 𝑖. And we can now see that we have a
complex number with a real component of four and an imaginary component of negative