Question

Gregory saw that the answer to a problem in his friend’s textbook was 4+2i. This is an example of which type of number?

an integer
a rational number
a complex number
an irrational number

Answer 1

A complex number.
Complex number is:
a+bi

Answer 2

For this case the first thing you should know is that a complex number is written as follows:
a + bi
Where,
a: real part
bi: imaginary part
We note that for this case:
a = 4
b = 2
Obtaining the following complex number:
4 + 2i
Answer:
This is an example of:
a complex number