Simplify the following:
-11y² + 9y

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?

Ascientist places 24 cells in a petri dish. she knows the cells grow at an exponential rate, doubling in number every hour. how long will it take (in hours) for there to be 1100 cells in the dish? time to 1100 cells: 5.51832530 hours how long will it take to reach 110 cells? time to 110 cells : 2.1963972 hours what is the average rate of change in the number of cells between 9 hours and 11 hours? average rate of change: cells per hour what is the instantaneous rate of change after 7 hours? instantaneous rate of change: cells per hour note: you can earn partial credit on this problem.

The distance between a football fsaid and a parking lot is 135 feet. what is that length in yards? 2 mickey needs to cut pieces of ribbon that are each 1 meter long to tie onto balloons. if he has 8 pieces of ribbon that are each 1 dekameter long, how many 1-meter pieces of ribbon can he cut? show work