1. For what positive number is the sum of its reciprocal and five times its square a minimum? 2. For what positive number is the sum of its reciprocal and four times its square a minimum? 3. The...

1. For what positive number is the sum of its reciprocal and five times its square a minimum?

2. For what positive number is the sum of its reciprocal and four times its square a minimum?

3. The amount of money that customers deposit in a bank in savings accounts is directly proportional to the interest rate that the bank pays on that money. Suppose a bank is able to loan out all the money deposited in its savings accounts at an interest rate of 18%. What interest rate should it pay on its savings accounts in order to maximize profit?