Which operation is not closed for polynomials? a) −(x2 + 4x + 5)(8x2 + 3x + 4) b) (7x2 + 2x + 3) + (3x2 − 5x + 4) c) (x2 + 2x + 5) − (x2 − 2x + 9) d) (x3 + 4x − 5)/(x5 − 2x + 2)

The physical fitness of an athlete is often measured by how much oxygen the athlete takes in (which is recorded in milliliters per kilogram, ml/kg). the mean maximum oxygen uptake for elite athletes has been found to be 60 with a standard deviation of 7.2. assume that the distribution is approximately normal.

Asocial networking site currently has 400,000 active members, and that figure is predicted to increase by 32% each year. the following expression represents the number of active members on the site after t years.

The graph shows the decibel measure for sounds depending on how many times as intense they are as the threshold of sound. noise in a quiet room is 500 times as intense as the threshold of sound. what is the decibel measurement for the quiet room? 20 decibels28 decibels200 decibels280 decibels