Which expression represents the number 12.3 rewritten in a+bi form? 12.3+0i
1+12.3i
12.3+i
0+12.3i

The correct option is;

12.3 + 0i

Step-by-step explanation:

The form a + b·i is the complex number form where the variables a and b are real numbers and i is the square root of -1, √(-1) that is i² = -1. As the answer to  √(-1), cannot be found among the real numbers, i, is known as an imaginary number.

As such  a given complex number of the form a + b·i, has a real, part or component, a, and an imaginary part, b.

The number 12.3, is a real number, therefore, representing the number in a complex number format, the imaginary part, b, would be zero, as follows;

12.3 + 0·i

answer: $420.00

step-by-step explanation:   multiply $400.00 by 5%.

400.00*.05=20

400+20 = 420