When we use both... And as subject, the predicate is plural, but we should pay attention to the article before the two nouns?
Yes, but this article is a definite article
If the complex Z is equal to the square root of its conjugate complex, then Z is
a+bi
The conjugate complex number is
a-bi
(a+bi)²=(a-bi)²
a²+abi-b²=a²-abi-b²
abi=0
ab=0
So a = 0 or B = 0
in other words
If the complex Z is equal to the square root of its conjugate complex, then Z is a real number or a pure imaginary number
Z is a complex number and the conjugate of Z * Z + the conjugate of Z / z = 1 + I to find Z
It's about the plural