Which statement correctly identifies the standard form of a complex number?

Which statement correctly identifies the standard form of a complex number?

• A. a + bi
• B. a + bj
• C. a + b
• D. a + ib^2

Answer: (A)

A complex number is written in standard form as a + bi, where a is the real part and b is the real coefficient of the imaginary unit i (with i^2 = -1). The expression a + bi matches this pattern exactly: you have the real part a and the imaginary part b times i. The other forms don’t fit the standard pattern: using bj switches i to a different symbol; a + b has no imaginary part at all; and ib^2 would place a squared coefficient with i, whereas the conventional standard form uses the imaginary coefficient as a simple real number multiplying i.

A complex number is written in standard form as a + bi, where a is the real part and b is the real coefficient of the imaginary unit i (with i^2 = -1). The expression a + bi matches this pattern exactly: you have the real part a and the imaginary part b times i. The other forms don’t fit the standard pattern: using bj switches i to a different symbol; a + b has no imaginary part at all; and ib^2 would place a squared coefficient with i, whereas the conventional standard form uses the imaginary coefficient as a simple real number multiplying i.