What is the square root of -1?

Create a real-life situation and create a system and show how it might be modeled algebraically with a system of equations (or inequalities) show all work include a few sentences explaining the situation, your variables of choice and what each represents, and how you would set it up and solve it algebraically. !

Solve each quadratic equation by factoring and using the zero product property. 10x + 6 = -2x^2 -2

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?