Given that a=2, b=-1 and c=3 work out b(squared) - 2ac

What basic trigonometric identity would you use to verify that csc x sec x cot x = csc^(2)x

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?

Can someone me with this problem i don't understand i need