Question

question 3 of 10
a number written in the form $a + bi$ is called a ______ number.

a. quadratic
b. discriminant
c. linear
d. complex

Explanation:

To solve this, we analyze each option:

• Option A: A quadratic is a polynomial of degree 2 (e.g., \(ax^2 + bx + c\)), not related to \(a + bi\) form.
• Option B: The discriminant is part of the quadratic formula (\(b^2 - 4ac\)) and not a number in \(a + bi\) form.
• Option C: A linear expression is of the form \(mx + n\), not \(a + bi\).
• Option D: By definition, a complex number is written as \(a + bi\), where \(a\) and \(b\) are real numbers and \(i=\sqrt{-1}\).

Answer:

D. complex