20 points! 13. tell whether the sequence is arithmetic. if it is, what is the common difference? 2, 7, 13, 20, . . a. yes; 5 b. yes; 6 c. yes; 2 d. no 14. tell whether the sequence is arithmetic. if it is, what is the common difference? 19, 12, 5, -2 a. no b. yes; 1/7 c. yes; 7 d. yes; -7 15. new grass seeds grow rapidly. a grass seed has grown to 12 millimeters tall. tomorrow it will be 23 millimeters tall, the next day it will be 34 millimeters tall, and on the next day it will be 45 millimeters tall. write a rule to represent the height of the bean plant as an arithmetic sequence. how tall will the plant be in 15 days? a. a(n) = 16 + (n - 1)11; 194 milliimeters b. a(n) = 12 + (n - 1)11; 194 milliimeters c. a(n) = 13n; 195 millimeters d. a(n) = 12n; 180 millimeters