For this case the first thing we should know is that a complex number is a number of the form: a + bi Where, a: real part bi: imaginary part The real part is represented on the horizontal axis of the complex plane The imaginary part is represented on the vertical axis of the complex plane We are looking for a unique number is: above the real axis and to the left of the imaginary axis Equivalently: Second quadrant of the complex plane. Using the definition, the number that complies with this feature is: 4i-1 Answer: c) 4i-1
