Question

what type of number is 85.72i? choose all answers that apply: a real b imaginary c complex

Explanation:

• A real number is a number that can be represented on the number line and does not involve the imaginary unit \(i\). Since \(85.72i\) has \(i\), it is not real.
• An imaginary number is a number of the form \(bi\) where \(b\) is a real number and \(b

eq0\). Here, \(85.72i\) is in the form \(bi\) with \(b = 85.72\) (a real number), so it is imaginary.

• A complex number is a number of the form \(a + bi\) where \(a\) and \(b\) are real numbers. For \(85.72i\), we can write it as \(0+85.72i\) (where \(a = 0\) and \(b = 85.72\)), so it is a complex number.

Answer:

B. Imaginary, C. Complex