What to do when on the quadratic formula the square root number is negative

A) if $50000 is invested in a bank account that pays 9.3% of interest compounded on a six-monthly basis, how much money will be in the account after 3 and 12 years? b) if matusalen's father had put $2.0 in the bank when he was born and there, how long would matusalen have had to his death (969 years later) if the interest was 7% per year composed each month and weekly?

Which graph corresponds to the function f(x) = x2 + 4x – 1?

The border line of the linear inequality 4x + 7y < 5 is dotted true or false?