Write the product as a sum.
17 sin (x/2)cos(x/4)

Solve the system of equations. y= 2x y= x^2 - 15

The difference between two numbers is one. three times the larger number minus two times the smaller number is 9. what are the two numbers

Sam opened a money-market account that pays 3% simple interest. he started the account with $7,000 and made no further deposits. when he closed the account, he had earned $420 in interest. how long did he keep his account open?