What is the square root of -1?

Which expression is equivalent to (9x - 3 1/ + 1 3/8)

Apatient is to be given 35 milligrams of demerol every 4 hours. you have demerol 50 milligrams/milliliter in stock. how many milliliters should be given per dose?

Solve each quadratic equation by factoring and using the zero product property. n^2 - 49 = 0