In how many different ways can 6 books be arranged on a shelf? 6 120 720

One of the inventors of integrated circuits observed that the number of transistors that fit on an integrated circuit will double every 24 months. what type of relationship most appropriately models this situation?

For what value of (y) is 3^3/3^y =1/9

X+ y = 5 ; x - y =3 solve using linear combination