How do we use imaginary numbers?

Imaginary numbers are common in math when using negative numbers in some situations. For example taking the square root of an negative number. We define i equal to the square root of negative 1, also called the imaginary unit. We call i the solution to the equation i squared plus 1 equal 0, or i squared equal negative 1. i to the first power equals i. i to the second power equals -1. i to the third power equals -i. And i to the forth power equals 1. For example taking the square root of -25. The negative sign automatically becomes an i so you can take that out. Now you can factor out 25 which is 5 times 5. The 5 comes out of the radical sign so now you have an i and a 5 out. Your answer would now be 5i. The number always comes before the i.