9 less than twice the number

The multiplication property of zero states that the product of any number and 0 is 0. what must be true about either a or b to make ab=0

Each of the walls of a room with square dimensions has been built with two pieces of sheetrock, a smaller one and a larger one. the length of all the smaller ones is the same and is stored in the variable small. similarly, the length of all the larger ones is the same and is stored in the variable large. write a single expression whose value is the total area of this room. do not use any method invocations.

Which graph has a rate of change of zero