Simplify 3 square root of 10 end root plus 7 square root of 15 end root minus 6 square root of 10 end root minus 4 square root of 15 . (1 point) 3 square root of 10 end root minus 3 square root of 15 3 square root of 15 end root minus 3 square root of 10 3 square root of 30 end root minus 3 square root of 20 3 square root of 20 end root minus 3 square root of 30

At the beginning of a call to the cable company, a message tells customers, "after you finish talking to our customer service representative, you will be asked to take a five-question survey about the level of service you recieved. it would be appreciated if you could stay on the line to answer the survey questions." what type of sampling is the cable company using?