## College Algebra (10th Edition)

RECALL: In the complex number $a+bi$, $a$ is the real number part while $bi$ is the imaginary number part. Note that when $b=0$, the complex number $a+bi$ becomes $a+oi=a$, which is a real number. . This means that the set of real numbers is a subset of the set of complex numbers. Thus, the given statement is true.