What is the square root of -1? Why is it necessary to define i?

Based upon past experience, barry expects no overdrafts. he expects no 2nd copies of statements. barry estimates that he will use network atms about 5 times a month with either bank. barry decides in the end to choose eecu. assuming that both banks provide the necessary services equally well, and based upon the tables of fees given above, how much can barry reasonably expect to save annually by choosing eecu in this case over e-town bank? a. $72 b. $78 c. $144 d. $24

Acompany wants to reduce the dimensions of its logo by one fourth to use on business cards. if the area of the original logo is 4 square inches, what is the area of the logo that will be used on the business cards?

In need of in the diagram, ∠abc is a right angle. ∠dbc = 30°27'40". find the measure of ∠abd.