What is the standard form of a complex number?

What is the standard form of a complex number?

• A. a - bi
• B. bi + a
• C. a + bi
• D. -a + bi

Answer: (C)

Standard form writes the real part first, then the imaginary part with the imaginary unit i. A complex number is written as a + bi, where a and b are real numbers and i^2 = -1. This ordering makes it easy to see the real component and the magnitude of the imaginary component separately. So the form a + bi is the canonical one. Writing bi + a would give the same number but in a nonstandard order. Writing a − bi changes the sign of the imaginary part, which corresponds to a different complex number unless you also change b. Similarly, −a + bi has a different real part altogether.

Standard form writes the real part first, then the imaginary part with the imaginary unit i. A complex number is written as a + bi, where a and b are real numbers and i^2 = -1. This ordering makes it easy to see the real component and the magnitude of the imaginary component separately.

So the form a + bi is the canonical one. Writing bi + a would give the same number but in a nonstandard order. Writing a − bi changes the sign of the imaginary part, which corresponds to a different complex number unless you also change b. Similarly, −a + bi has a different real part altogether.